#2389 - Longest Subsequence With Limited Sum

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Array Sorting Greedy Binary Search Prefix Sum

Problem Description

You are given an integer array nums of length n, and an integer array queries of length m.

Return an array answer of length m where answer[i] is the maximum size of a subsequence that you can take from nums such that the sum of its elements is less than or equal to queries[i].

A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements.

Solution

/**
 * @param {number[]} nums
 * @param {number[]} queries
 * @return {number[]}
 */
var answerQueries = function(nums, queries) {
  nums.sort((a, b) => a - b);
  const prefixSums = [0];
  for (const num of nums) {
    prefixSums.push(prefixSums.at(-1) + num);
  }

  const result = new Array(queries.length);
  for (let i = 0; i < queries.length; i++) {
    let left = 0;
    let right = nums.length;
    while (left < right) {
      const mid = Math.floor((left + right + 1) / 2);
      if (prefixSums[mid] <= queries[i]) {
        left = mid;
      } else {
        right = mid - 1;
      }
    }
    result[i] = left;
  }

  return result;
};