0665-non-decreasing-array.js

/**
 * 665. Non-decreasing Array
 * https://leetcode.com/problems/non-decreasing-array/
 * Difficulty: Medium
 *
 * Given an array nums with n integers, your task is to check if it could become non-decreasing
 * by modifying at most one element.
 *
 * We define an array is non-decreasing if nums[i] <= nums[i + 1] holds for every i (0-based)
 * such that (0 <= i <= n - 2).
 */

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var checkPossibility = function(nums) {
  let count = 0;

  for (let i = 0; i < nums.length - 1; i++) {
    if (nums[i] > nums[i + 1]) {
      count++;
      if (count > 1) return false;
      if (i > 0 && nums[i - 1] > nums[i + 1]) {
        nums[i + 1] = nums[i];
      } else {
        nums[i] = nums[i + 1];
      }
    }
  }

  return true;
};