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1622. Fancy Sequence

Description

Write an API that generates fancy sequences using the append, addAll, and multAll operations.

Implement the Fancy class:

  • Fancy() Initializes the object with an empty sequence.
  • void append(val) Appends an integer val to the end of the sequence.
  • void addAll(inc) Increments all existing values in the sequence by an integer inc.
  • void multAll(m) Multiplies all existing values in the sequence by an integer m.
  • int getIndex(idx) Gets the current value at index idx (0-indexed) of the sequence modulo 109 + 7. If the index is greater or equal than the length of the sequence, return -1.

 

Example 1:

Input
["Fancy", "append", "addAll", "append", "multAll", "getIndex", "addAll", "append", "multAll", "getIndex", "getIndex", "getIndex"]
[[], [2], [3], [7], [2], [0], [3], [10], [2], [0], [1], [2]]
Output
[null, null, null, null, null, 10, null, null, null, 26, 34, 20]

Explanation
Fancy fancy = new Fancy();
fancy.append(2);   // fancy sequence: [2]
fancy.addAll(3);   // fancy sequence: [2+3] -> [5]
fancy.append(7);   // fancy sequence: [5, 7]
fancy.multAll(2);  // fancy sequence: [5*2, 7*2] -> [10, 14]
fancy.getIndex(0); // return 10
fancy.addAll(3);   // fancy sequence: [10+3, 14+3] -> [13, 17]
fancy.append(10);  // fancy sequence: [13, 17, 10]
fancy.multAll(2);  // fancy sequence: [13*2, 17*2, 10*2] -> [26, 34, 20]
fancy.getIndex(0); // return 26
fancy.getIndex(1); // return 34
fancy.getIndex(2); // return 20

 

Constraints:

  • 1 <= val, inc, m <= 100
  • 0 <= idx <= 105
  • At most 105 calls total will be made to append, addAll, multAll, and getIndex.

Solutions

Solution 1

Thinking

We must append, add to or multiply the whole current prefix, and query one index, up to \(10^5\) times. Updating every element on each call is too slow.

Append writes a new rightmost position; add and multiply are affine range updates on \([1,\textit{idx}]\). A segment tree stores a value and lazy tags \((\textit{mul},\textit{add})\), composing multiply before add.

Nodes are created on demand over \([1,10^5]\): append is a point write, addAll/multAll update a prefix, and getIndex is a point query, all modulo \(10^9+7\).

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MOD = int(1e9 + 7)


class Node:
    def __init__(self, l, r):
        self.left = None
        self.right = None
        self.l = l
        self.r = r
        self.mid = (l + r) >> 1
        self.v = 0
        self.add = 0
        self.mul = 1


class SegmentTree:
    def __init__(self):
        self.root = Node(1, int(1e5 + 1))

    def modifyAdd(self, l, r, inc, node=None):
        if l > r:
            return
        if node is None:
            node = self.root
        if node.l >= l and node.r <= r:
            node.v = (node.v + (node.r - node.l + 1) * inc) % MOD
            node.add += inc
            return
        self.pushdown(node)
        if l <= node.mid:
            self.modifyAdd(l, r, inc, node.left)
        if r > node.mid:
            self.modifyAdd(l, r, inc, node.right)
        self.pushup(node)

    def modifyMul(self, l, r, m, node=None):
        if l > r:
            return
        if node is None:
            node = self.root
        if node.l >= l and node.r <= r:
            node.v = (node.v * m) % MOD
            node.add = (node.add * m) % MOD
            node.mul = (node.mul * m) % MOD
            return
        self.pushdown(node)
        if l <= node.mid:
            self.modifyMul(l, r, m, node.left)
        if r > node.mid:
            self.modifyMul(l, r, m, node.right)
        self.pushup(node)

    def query(self, l, r, node=None):
        if l > r:
            return 0
        if node is None:
            node = self.root
        if node.l >= l and node.r <= r:
            return node.v
        self.pushdown(node)
        v = 0
        if l <= node.mid:
            v = (v + self.query(l, r, node.left)) % MOD
        if r > node.mid:
            v = (v + self.query(l, r, node.right)) % MOD
        return v

    def pushup(self, node):
        node.v = (node.left.v + node.right.v) % MOD

    def pushdown(self, node):
        if node.left is None:
            node.left = Node(node.l, node.mid)
        if node.right is None:
            node.right = Node(node.mid + 1, node.r)
        left, right = node.left, node.right
        if node.add != 0 or node.mul != 1:
            left.v = (left.v * node.mul + (left.r - left.l + 1) * node.add) % MOD
            right.v = (right.v * node.mul + (right.r - right.l + 1) * node.add) % MOD
            left.add = (left.add * node.mul + node.add) % MOD
            right.add = (right.add * node.mul + node.add) % MOD
            left.mul = (left.mul * node.mul) % MOD
            right.mul = (right.mul * node.mul) % MOD
            node.add = 0
            node.mul = 1


class Fancy:
    def __init__(self):
        self.n = 0
        self.tree = SegmentTree()

    def append(self, val: int) -> None:
        self.n += 1
        self.tree.modifyAdd(self.n, self.n, val)

    def addAll(self, inc: int) -> None:
        self.tree.modifyAdd(1, self.n, inc)

    def multAll(self, m: int) -> None:
        self.tree.modifyMul(1, self.n, m)

    def getIndex(self, idx: int) -> int:
        return -1 if idx >= self.n else self.tree.query(idx + 1, idx + 1)


# Your Fancy object will be instantiated and called as such:
# obj = Fancy()
# obj.append(val)
# obj.addAll(inc)
# obj.multAll(m)
# param_4 = obj.getIndex(idx)

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class Node {
    Node left;
    Node right;
    int l;
    int r;
    int mid;
    long v;
    long add;
    long mul = 1;

    public Node(int l, int r) {
        this.l = l;
        this.r = r;
        this.mid = (l + r) >> 1;
    }
}

class SegmentTree {
    private Node root = new Node(1, (int) 1e5 + 1);
    private static final int MOD = (int) 1e9 + 7;

    public SegmentTree() {
    }

    public void modifyAdd(int l, int r, int inc) {
        modifyAdd(l, r, inc, root);
    }

    public void modifyAdd(int l, int r, int inc, Node node) {
        if (l > r) {
            return;
        }
        if (node.l >= l && node.r <= r) {
            node.v = (node.v + (node.r - node.l + 1) * inc) % MOD;
            node.add = (node.add + inc) % MOD;
            return;
        }
        pushdown(node);
        if (l <= node.mid) {
            modifyAdd(l, r, inc, node.left);
        }
        if (r > node.mid) {
            modifyAdd(l, r, inc, node.right);
        }
        pushup(node);
    }

    public void modifyMul(int l, int r, int m) {
        modifyMul(l, r, m, root);
    }

    public void modifyMul(int l, int r, int m, Node node) {
        if (l > r) {
            return;
        }
        if (node.l >= l && node.r <= r) {
            node.v = (node.v * m) % MOD;
            node.add = (node.add * m) % MOD;
            node.mul = (node.mul * m) % MOD;
            return;
        }
        pushdown(node);
        if (l <= node.mid) {
            modifyMul(l, r, m, node.left);
        }
        if (r > node.mid) {
            modifyMul(l, r, m, node.right);
        }
        pushup(node);
    }

    public int query(int l, int r) {
        return query(l, r, root);
    }

    public int query(int l, int r, Node node) {
        if (l > r) {
            return 0;
        }
        if (node.l >= l && node.r <= r) {
            return (int) node.v;
        }
        pushdown(node);
        int v = 0;
        if (l <= node.mid) {
            v = (v + query(l, r, node.left)) % MOD;
        }
        if (r > node.mid) {
            v = (v + query(l, r, node.right)) % MOD;
        }
        return v;
    }

    public void pushup(Node node) {
        node.v = (node.left.v + node.right.v) % MOD;
    }

    public void pushdown(Node node) {
        if (node.left == null) {
            node.left = new Node(node.l, node.mid);
        }
        if (node.right == null) {
            node.right = new Node(node.mid + 1, node.r);
        }
        if (node.add != 0 || node.mul != 1) {
            Node left = node.left, right = node.right;
            left.v = (left.v * node.mul + (left.r - left.l + 1) * node.add) % MOD;
            right.v = (right.v * node.mul + (right.r - right.l + 1) * node.add) % MOD;
            left.add = (left.add * node.mul + node.add) % MOD;
            right.add = (right.add * node.mul + node.add) % MOD;
            left.mul = (left.mul * node.mul) % MOD;
            right.mul = (right.mul * node.mul) % MOD;
            node.add = 0;
            node.mul = 1;
        }
    }
}

class Fancy {
    private int n;
    private SegmentTree tree = new SegmentTree();

    public Fancy() {
    }

    public void append(int val) {
        ++n;
        tree.modifyAdd(n, n, val);
    }

    public void addAll(int inc) {
        tree.modifyAdd(1, n, inc);
    }

    public void multAll(int m) {
        tree.modifyMul(1, n, m);
    }

    public int getIndex(int idx) {
        return idx >= n ? -1 : tree.query(idx + 1, idx + 1);
    }
}

/**
 * Your Fancy object will be instantiated and called as such:
 * Fancy obj = new Fancy();
 * obj.append(val);
 * obj.addAll(inc);
 * obj.multAll(m);
 * int param_4 = obj.getIndex(idx);
 */

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const int MOD = 1e9 + 7;

class Node {
public:
    Node* left;
    Node* right;
    int l;
    int r;
    int mid;
    long long v;
    long long add;
    long long mul;

    Node(int l, int r) {
        this->l = l;
        this->r = r;
        this->mid = (l + r) >> 1;
        this->left = this->right = nullptr;
        v = add = 0;
        mul = 1;
    }
};

class SegmentTree {
private:
    Node* root;

public:
    SegmentTree() {
        root = new Node(1, 1e5 + 1);
    }

    void modifyAdd(int l, int r, int inc) {
        modifyAdd(l, r, inc, root);
    }

    void modifyAdd(int l, int r, int inc, Node* node) {
        if (l > r) return;
        if (node->l >= l && node->r <= r) {
            node->v = (node->v + (node->r - node->l + 1) * inc) % MOD;
            node->add = (node->add + inc) % MOD;
            return;
        }
        pushdown(node);
        if (l <= node->mid) modifyAdd(l, r, inc, node->left);
        if (r > node->mid) modifyAdd(l, r, inc, node->right);
        pushup(node);
    }

    void modifyMul(int l, int r, int m) {
        modifyMul(l, r, m, root);
    }

    void modifyMul(int l, int r, int m, Node* node) {
        if (l > r) return;
        if (node->l >= l && node->r <= r) {
            node->v = (node->v * m) % MOD;
            node->add = (node->add * m) % MOD;
            node->mul = (node->mul * m) % MOD;
            return;
        }
        pushdown(node);
        if (l <= node->mid) modifyMul(l, r, m, node->left);
        if (r > node->mid) modifyMul(l, r, m, node->right);
        pushup(node);
    }

    int query(int l, int r) {
        return query(l, r, root);
    }

    int query(int l, int r, Node* node) {
        if (l > r) return 0;
        if (node->l >= l && node->r <= r) return node->v;
        pushdown(node);
        int v = 0;
        if (l <= node->mid) v = (v + query(l, r, node->left)) % MOD;
        if (r > node->mid) v = (v + query(l, r, node->right)) % MOD;
        return v;
    }

    void pushup(Node* node) {
        node->v = (node->left->v + node->right->v) % MOD;
    }

    void pushdown(Node* node) {
        if (!node->left) node->left = new Node(node->l, node->mid);
        if (!node->right) node->right = new Node(node->mid + 1, node->r);
        if (node->add || node->mul != 1) {
            long add = node->add, mul = node->mul;
            Node* left = node->left;
            Node* right = node->right;
            left->v = (left->v * mul + (left->r - left->l + 1) * add) % MOD;
            right->v = (right->v * mul + (right->r - right->l + 1) * add) % MOD;
            left->add = (left->add * mul + add) % MOD;
            right->add = (right->add * mul + add) % MOD;
            left->mul = (left->mul * mul) % MOD;
            right->mul = (right->mul * mul) % MOD;
            node->add = 0;
            node->mul = 1;
        }
    }
};

class Fancy {
public:
    int n;
    SegmentTree* tree;

    Fancy() {
        n = 0;
        tree = new SegmentTree();
    }

    void append(int val) {
        ++n;
        tree->modifyAdd(n, n, val);
    }

    void addAll(int inc) {
        tree->modifyAdd(1, n, inc);
    }

    void multAll(int m) {
        tree->modifyMul(1, n, m);
    }

    int getIndex(int idx) {
        return idx >= n ? -1 : tree->query(idx + 1, idx + 1);
    }
};

/**
 * Your Fancy object will be instantiated and called as such:
 * Fancy* obj = new Fancy();
 * obj->append(val);
 * obj->addAll(inc);
 * obj->multAll(m);
 * int param_4 = obj->getIndex(idx);
 */

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const MOD int64 = 1e9 + 7

type Node struct {
    left  *Node
    right *Node
    l     int
    r     int
    mid   int
    v     int64
    add   int64
    mul   int64
}

func newNode(l, r int) *Node {
    return &Node{
        l:   l,
        r:   r,
        mid: (l + r) >> 1,
        mul: 1,
    }
}

type SegmentTree struct {
    root *Node
}

func newSegmentTree() *SegmentTree {
    return &SegmentTree{
        root: newNode(1, 100001),
    }
}

func (t *SegmentTree) modifyAdd(l, r int, inc int64) {
    t.modifyAddNode(l, r, inc, t.root)
}

func (t *SegmentTree) modifyAddNode(l, r int, inc int64, node *Node) {
    if l > r {
        return
    }

    if node.l >= l && node.r <= r {
        node.v = (node.v + int64(node.r-node.l+1)*inc) % MOD
        node.add = (node.add + inc) % MOD
        return
    }

    t.pushdown(node)

    if l <= node.mid {
        t.modifyAddNode(l, r, inc, node.left)
    }

    if r > node.mid {
        t.modifyAddNode(l, r, inc, node.right)
    }

    t.pushup(node)
}

func (t *SegmentTree) modifyMul(l, r int, m int64) {
    t.modifyMulNode(l, r, m, t.root)
}

func (t *SegmentTree) modifyMulNode(l, r int, m int64, node *Node) {
    if l > r {
        return
    }

    if node.l >= l && node.r <= r {
        node.v = node.v * m % MOD
        node.add = node.add * m % MOD
        node.mul = node.mul * m % MOD
        return
    }

    t.pushdown(node)

    if l <= node.mid {
        t.modifyMulNode(l, r, m, node.left)
    }

    if r > node.mid {
        t.modifyMulNode(l, r, m, node.right)
    }

    t.pushup(node)
}

func (t *SegmentTree) query(l, r int) int {
    return int(t.queryNode(l, r, t.root))
}

func (t *SegmentTree) queryNode(l, r int, node *Node) int64 {
    if l > r {
        return 0
    }

    if node.l >= l && node.r <= r {
        return node.v
    }

    t.pushdown(node)

    var v int64

    if l <= node.mid {
        v = (v + t.queryNode(l, r, node.left)) % MOD
    }

    if r > node.mid {
        v = (v + t.queryNode(l, r, node.right)) % MOD
    }

    return v
}

func (t *SegmentTree) pushup(node *Node) {
    node.v = (node.left.v + node.right.v) % MOD
}

func (t *SegmentTree) pushdown(node *Node) {

    if node.left == nil {
        node.left = newNode(node.l, node.mid)
    }

    if node.right == nil {
        node.right = newNode(node.mid+1, node.r)
    }

    if node.add != 0 || node.mul != 1 {

        add := node.add
        mul := node.mul

        left := node.left
        right := node.right

        left.v = (left.v*mul + int64(left.r-left.l+1)*add) % MOD
        right.v = (right.v*mul + int64(right.r-right.l+1)*add) % MOD

        left.add = (left.add*mul + add) % MOD
        right.add = (right.add*mul + add) % MOD

        left.mul = left.mul * mul % MOD
        right.mul = right.mul * mul % MOD

        node.add = 0
        node.mul = 1
    }
}

type Fancy struct {
    n    int
    tree *SegmentTree
}

func Constructor() Fancy {
    return Fancy{
        tree: newSegmentTree(),
    }
}

func (f *Fancy) Append(val int) {
    f.n++
    f.tree.modifyAdd(f.n, f.n, int64(val))
}

func (f *Fancy) AddAll(inc int) {
    f.tree.modifyAdd(1, f.n, int64(inc))
}

func (f *Fancy) MultAll(m int) {
    f.tree.modifyMul(1, f.n, int64(m))
}

func (f *Fancy) GetIndex(idx int) int {
    if idx >= f.n {
        return -1
    }
    return f.tree.query(idx+1, idx+1)
}

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const MOD = 1000000007n;

class Node {
    left: Node | null = null;
    right: Node | null = null;

    l: number;
    r: number;
    mid: number;

    v = 0n;
    add = 0n;
    mul = 1n;

    constructor(l: number, r: number) {
        this.l = l;
        this.r = r;
        this.mid = (l + r) >> 1;
    }
}

class SegmentTree {
    root: Node;

    constructor() {
        this.root = new Node(1, 100001);
    }

    modifyAdd(l: number, r: number, inc: bigint, node: Node = this.root): void {
        if (l > r) return;

        if (node.l >= l && node.r <= r) {
            node.v = (node.v + BigInt(node.r - node.l + 1) * inc) % MOD;
            node.add = (node.add + inc) % MOD;
            return;
        }

        this.pushdown(node);

        if (l <= node.mid) this.modifyAdd(l, r, inc, node.left!);
        if (r > node.mid) this.modifyAdd(l, r, inc, node.right!);

        this.pushup(node);
    }

    modifyMul(l: number, r: number, m: bigint, node: Node = this.root): void {
        if (l > r) return;

        if (node.l >= l && node.r <= r) {
            node.v = (node.v * m) % MOD;
            node.add = (node.add * m) % MOD;
            node.mul = (node.mul * m) % MOD;
            return;
        }

        this.pushdown(node);

        if (l <= node.mid) this.modifyMul(l, r, m, node.left!);
        if (r > node.mid) this.modifyMul(l, r, m, node.right!);

        this.pushup(node);
    }

    query(l: number, r: number, node: Node = this.root): bigint {
        if (l > r) return 0n;

        if (node.l >= l && node.r <= r) return node.v;

        this.pushdown(node);

        let v = 0n;

        if (l <= node.mid) v = (v + this.query(l, r, node.left!)) % MOD;
        if (r > node.mid) v = (v + this.query(l, r, node.right!)) % MOD;

        return v;
    }

    pushup(node: Node): void {
        node.v = (node.left!.v + node.right!.v) % MOD;
    }

    pushdown(node: Node): void {
        if (!node.left) node.left = new Node(node.l, node.mid);
        if (!node.right) node.right = new Node(node.mid + 1, node.r);

        if (node.add !== 0n || node.mul !== 1n) {
            const add = node.add;
            const mul = node.mul;

            const left = node.left!;
            const right = node.right!;

            left.v = (left.v * mul + BigInt(left.r - left.l + 1) * add) % MOD;
            right.v = (right.v * mul + BigInt(right.r - right.l + 1) * add) % MOD;

            left.add = (left.add * mul + add) % MOD;
            right.add = (right.add * mul + add) % MOD;

            left.mul = (left.mul * mul) % MOD;
            right.mul = (right.mul * mul) % MOD;

            node.add = 0n;
            node.mul = 1n;
        }
    }
}

class Fancy {
    n = 0;
    tree = new SegmentTree();

    append(val: number): void {
        this.n++;
        this.tree.modifyAdd(this.n, this.n, BigInt(val));
    }

    addAll(inc: number): void {
        this.tree.modifyAdd(1, this.n, BigInt(inc));
    }

    multAll(m: number): void {
        this.tree.modifyMul(1, this.n, BigInt(m));
    }

    getIndex(idx: number): number {
        if (idx >= this.n) return -1;
        return Number(this.tree.query(idx + 1, idx + 1));
    }
}

/**
 * Your Fancy object will be instantiated and called as such:
 * var obj = new Fancy()
 * obj.append(val)
 * obj.addAll(inc)
 * obj.multAll(m)
 * var param_4 = obj.getIndex(idx)
 */

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