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1618. Maximum Font to Fit a Sentence in a Screen πŸ”’

Description

You are given a string text. We want to display text on a screen of width w and height h. You can choose any font size from array fonts, which contains the available font sizes in ascending order.

You can use the FontInfo interface to get the width and height of any character at any available font size.

The FontInfo interface is defined as such:

interface FontInfo {
  // Returns the width of character ch on the screen using font size fontSize.
  // O(1) per call
  public int getWidth(int fontSize, char ch);

  // Returns the height of any character on the screen using font size fontSize.
  // O(1) per call
  public int getHeight(int fontSize);
}

The calculated width of text for some fontSize is the sum of every getWidth(fontSize, text[i]) call for each 0 <= i < text.length (0-indexed). The calculated height of text for some fontSize is getHeight(fontSize). Note that text is displayed on a single line.

It is guaranteed that FontInfo will return the same value if you call getHeight or getWidth with the same parameters.

It is also guaranteed that for any font size fontSize and any character ch:

  • getHeight(fontSize) <= getHeight(fontSize+1)
  • getWidth(fontSize, ch) <= getWidth(fontSize+1, ch)

Return the maximum font size you can use to display text on the screen. If text cannot fit on the display with any font size, return -1.

 

Example 1:

Input: text = "helloworld", w = 80, h = 20, fonts = [6,8,10,12,14,16,18,24,36]
Output: 6

Example 2:

Input: text = "leetcode", w = 1000, h = 50, fonts = [1,2,4]
Output: 4

Example 3:

Input: text = "easyquestion", w = 100, h = 100, fonts = [10,15,20,25]
Output: -1

 

Constraints:

  • 1 <= text.length <= 50000
  • text contains only lowercase English letters.
  • 1 <= w <= 107
  • 1 <= h <= 104
  • 1 <= fonts.length <= 105
  • 1 <= fonts[i] <= 105
  • fonts is sorted in ascending order and does not contain duplicates.

Solutions

Solution 1

Thinking

Font sizes are sorted and larger sizes are harder to fit, so feasibility is monotone in the index and we can binary-search the largest feasible size.

A size fits when its height is at most \(h\) and the sum of character widths is at most \(w\), both via \(\texttt{FontInfo}\).

Binary-search the index range, \(\texttt{check}\) the midpoint, and raise the left end on success. Verify \(\textit{fonts}[\textit{left}]\) at the end.

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# """
# This is FontInfo's API interface.
# You should not implement it, or speculate about its implementation
# """
# class FontInfo(object):
#    Return the width of char ch when fontSize is used.
#    def getWidth(self, fontSize, ch):
#        """
#        :type fontSize: int
#        :type ch: char
#        :rtype int
#        """
#
#    def getHeight(self, fontSize):
#        """
#        :type fontSize: int
#        :rtype int
#        """
class Solution:
    def maxFont(
        self, text: str, w: int, h: int, fonts: List[int], fontInfo: 'FontInfo'
    ) -> int:
        def check(size):
            if fontInfo.getHeight(size) > h:
                return False
            return sum(fontInfo.getWidth(size, c) for c in text) <= w

        left, right = 0, len(fonts) - 1
        ans = -1
        while left < right:
            mid = (left + right + 1) >> 1
            if check(fonts[mid]):
                left = mid
            else:
                right = mid - 1
        return fonts[left] if check(fonts[left]) else -1

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/**
 * // This is the FontInfo's API interface.
 * // You should not implement it, or speculate about its implementation
 * interface FontInfo {
 *     // Return the width of char ch when fontSize is used.
 *     public int getWidth(int fontSize, char ch) {}
 *     // Return Height of any char when fontSize is used.
 *     public int getHeight(int fontSize)
 * }
 */
class Solution {
    public int maxFont(String text, int w, int h, int[] fonts, FontInfo fontInfo) {
        int left = 0, right = fonts.length - 1;
        while (left < right) {
            int mid = (left + right + 1) >> 1;
            if (check(text, fonts[mid], w, h, fontInfo)) {
                left = mid;
            } else {
                right = mid - 1;
            }
        }
        return check(text, fonts[left], w, h, fontInfo) ? fonts[left] : -1;
    }

    private boolean check(String text, int size, int w, int h, FontInfo fontInfo) {
        if (fontInfo.getHeight(size) > h) {
            return false;
        }
        int width = 0;
        for (char c : text.toCharArray()) {
            width += fontInfo.getWidth(size, c);
        }
        return width <= w;
    }
}

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/**
 * // This is the FontInfo's API interface.
 * // You should not implement it, or speculate about its implementation
 * class FontInfo {
 *   public:
 *     // Return the width of char ch when fontSize is used.
 *     int getWidth(int fontSize, char ch);
 *
 *     // Return Height of any char when fontSize is used.
 *     int getHeight(int fontSize)
 * };
 */
class Solution {
public:
    int maxFont(string text, int w, int h, vector<int>& fonts, FontInfo fontInfo) {
        auto check = [&](int size) {
            if (fontInfo.getHeight(size) > h) return false;
            int width = 0;
            for (char& c : text) {
                width += fontInfo.getWidth(size, c);
            }
            return width <= w;
        };
        int left = 0, right = fonts.size() - 1;
        while (left < right) {
            int mid = (left + right + 1) >> 1;
            if (check(fonts[mid])) {
                left = mid;
            } else {
                right = mid - 1;
            }
        }
        return check(fonts[left]) ? fonts[left] : -1;
    }
};

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/**
 * // This is the FontInfo's API interface.
 * // You should not implement it, or speculate about its implementation
 * function FontInfo() {
 *
 *      @param {number} fontSize
 *      @param {char} ch
 *      @return {number}
 *      this.getWidth = function(fontSize, ch) {
 *          ...
 *      };
 *
 *      @param {number} fontSize
 *      @return {number}
 *      this.getHeight = function(fontSize) {
 *          ...
 *      };
 * };
 */
/**
 * @param {string} text
 * @param {number} w
 * @param {number} h
 * @param {number[]} fonts
 * @param {FontInfo} fontInfo
 * @return {number}
 */
var maxFont = function (text, w, h, fonts, fontInfo) {
    const check = function (size) {
        if (fontInfo.getHeight(size) > h) {
            return false;
        }
        let width = 0;
        for (const c of text) {
            width += fontInfo.getWidth(size, c);
        }
        return width <= w;
    };
    let left = 0;
    let right = fonts.length - 1;
    while (left < right) {
        const mid = (left + right + 1) >> 1;
        if (check(fonts[mid])) {
            left = mid;
        } else {
            right = mid - 1;
        }
    }
    return check(fonts[left]) ? fonts[left] : -1;
};

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