Likou 209 - String with the Minimum Length - Sliding Window Method

Title description

Given an array of n positive integers and a positive integer target .

Find the contiguous subarray [numsl, numsl+1, ..., numsr-1, numsr] with the smallest length in the array that satisfies its sum ≥ target, and return its length.Returns 0 if no matching subarray exists.

Solution ideas

• Cage's vivid sliding window solution;
• First create two pointers first and last to point to the head of nums;
• Move the right pointer, and consider whether the value between first------last meets the condition of >= target every time it moves;
• If not satisfied, last continues to move to the right;
• If it is satisfied, the first pointer moves to the right;
• Count the number of elements between first-----last that satisfy the condition each time, record the minimum value, and return the minimum value.
• When returning, you should add a judgment condition to see if the sum condition is met. If the sum condition is not met, and the minimum value is not updated, return 0.

Input and output example

Code

class Solution {public int minSubArrayLen(int target, int[] nums) {int len ​​= nums.length;int first = 0;int sum = 0;int min = Integer.MAX_VALUE;for(int last = 0; last < len; last++){sum += nums[last];while(sum >= target){min = Math.min(min,last-first+1);sum -= nums[first++];}}return min == Integer.MAX_VALUE ? 0 : min;}}