shortest-unsorted-continuous-subarray.js

/**
 * Shortest Unsorted Continuous Subarray
 *
 * Given an integer array, you need to find one continuous subarray that
 * if you only sort this subarray in ascending order, then the whole array will be sorted in ascending order, too.
 *
 * You need to find the shortest such subarray and output its length.
 *
 * Example 1:
 *
 * Input: [2, 6, 4, 8, 10, 9, 15]
 * Output: 5
 *
 * Explanation: You need to sort [6, 4, 8, 10, 9] in ascending order to make the whole array sorted in ascending order.
 *
 * Note:
 *
 * - Then length of the input array is in range [1, 10,000].
 * - The input array may contain duplicates, so ascending order here means <=.
 */

/**
 * @param {number[]} nums
 * @return {number}
 */
const findUnsortedSubarray = nums => {
  let min = Infinity;
  let max = -Infinity;

  let flag = false;
  for (let i = 1; i < nums.length; i++) {
    if (nums[i] < nums[i - 1]) {
      flag = true;
    }
    if (flag) {
      min = Math.min(min, nums[i]);
    }
  }

  flag = false;
  for (let i = nums.length - 2; i >= 0; i--) {
    if (nums[i] > nums[i + 1]) {
      flag = true;
    }
    if (flag) {
      max = Math.max(max, nums[i]);
    }
  }

  let l, r;
  for (l = 0; l < nums.length; l++) {
    if (min < nums[l]) break;
  }
  for (r = nums.length - 1; r >= 0; r--) {
    if (max > nums[r]) break;
  }
  return r - l < 0 ? 0 : r - l + 1;
};