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by Sumit Chourasia | Nov 21, 2020 | Category :coding | Tags : algorithm array data-structure leetcode medium

Shortest Unsorted Continuous Subarray - Array - Medium - LeetCode

Shortest Unsorted Continuous Subarray - Array - Medium - LeetCode

Given an integer array nums, 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.

Return the shortest such subarray and output its length.

 

Example 1:

Input: nums = [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.
Example 2:

Input: nums = [1,2,3,4]
Output: 0
Example 3:

Input: nums = [1]
Output: 0
 

Constraints:

1 <= nums.length <= 104
-105 <= nums[i] <= 105

public class Solution {
    public int FindUnsortedSubarray(int[] nums) {
        var l = new int[nums.Length];
        var r = new int[nums.Length];
        
        int max = int.MinValue;
        for(int i=0;i<nums.Length;i++){
            if(nums[i]>max){
                max = nums[i];
            }
            l[i]=max;
        }
        
        int min = int.MaxValue;
        for(int i=nums.Length-1;i>=0;i--){
            if(nums[i]<min){
                min = nums[i];
            }
            r[i]=min;
        }
        
        int left = 0;
        for(int i=0;i<nums.Length;i++){
            if(l[i]!=r[i]){
                left = i;
                break;
            }
        }
        
        int right = 0;
        for(int i=nums.Length-1;i>=0;i--){
            if(l[i]!=r[i]){
                right=i;
                break;
            }
        }
        
        if(left == right){
            return 0;
        }
        
        return right - left + 1;
    }
}

Time Complexity: O(n)

Space Complexity: O(n)