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2777. Date Range Generator πŸ”’

Description

Given a start date start, an end date end, and a positive integer step, return a generator object that yields dates in the range from start to end inclusive.

The value of step indicates the number of days between consecutive yielded values.

All yielded dates must be in the string format YYYY-MM-DD.

 

Example 1:

Input: start = "2023-04-01", end = "2023-04-04", step = 1
Output: ["2023-04-01","2023-04-02","2023-04-03","2023-04-04"]
Explanation: 
const g = dateRangeGenerator(start, end, step);
g.next().value // '2023-04-01'
g.next().value // '2023-04-02'
g.next().value // '2023-04-03'
g.next().value // '2023-04-04'

Example 2:

Input: start = "2023-04-10", end = "2023-04-20", step = 3
Output: ["2023-04-10","2023-04-13","2023-04-16","2023-04-19"]
Explanation: 
const g = dateRangeGenerator(start, end, step);
g.next().value // '2023-04-10'
g.next().value // '2023-04-13'
g.next().value // '2023-04-16'
g.next().value // '2023-04-19'

Example 3:

Input: start = "2023-04-10", end = "2023-04-10", step = 1
Output: ["2023-04-10"]
Explanation: 
const g = dateRangeGenerator(start, end, step);
g.next().value // '2023-04-10'

 

Constraints:

  • new Date(start) <= new Date(end)
  • start and end dates are in the string format YYYY-MM-DD
  • 0 <= The difference in days between the start date and the end date <= 1500
  • 1 <= step <= 1000

Solutions

Solution 1

Thinking

Yield every date in a closed range with a fixed step. Manual Julian-day arithmetic is easy to get wrong at month ends; \(Date.setDate\) carries automatically.

Walk from the start through the end, \(yield\) the ISO date, then add \(step\) days. The generator pauses, so the whole range need not be materialized.

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function* dateRangeGenerator(start: string, end: string, step: number): Generator<string> {
    const startDate = new Date(start);
    const endDate = new Date(end);
    let currentDate = startDate;
    while (currentDate <= endDate) {
        yield currentDate.toISOString().slice(0, 10);
        currentDate.setDate(currentDate.getDate() + step);
    }
}

/**
 * const g = dateRangeGenerator('2023-04-01', '2023-04-04', 1);
 * g.next().value; // '2023-04-01'
 * g.next().value; // '2023-04-02'
 * g.next().value; // '2023-04-03'
 * g.next().value; // '2023-04-04'
 * g.next().done; // true
 */

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