#3355 - Zero Array Transformation I

Medium • View on LeetCode • View on GitHub

Problem Description

You are given an integer array nums of length n and a 2D array queries, where queries[i] = [li, ri].

For each queries[i]:

Select a subset of indices within the range [li, ri] in nums.
Decrement the values at the selected indices by 1.

A Zero Array is an array where all elements are equal to 0.

Return true if it is possible to transform nums into a Zero Array after processing all the queries sequentially, otherwise return false.

Solution

/**
 * @param {number[]} nums
 * @param {number[][]} queries
 * @return {boolean}
 */
var isZeroArray = function(nums, queries) {
  const maxDecrements = new Array(nums.length).fill(0);

  for (const [left, right] of queries) {
    maxDecrements[left]++;
    if (right + 1 < nums.length) {
      maxDecrements[right + 1]--;
    }
  }

  let currentDecrements = 0;
  for (let i = 0; i < nums.length; i++) {
    currentDecrements += maxDecrements[i];
    if (nums[i] > currentDecrements) {
      return false;
    }
  }

  return true;
};