leetcode 209 : Minimum Size Subarray Sum

Minimum Size Subarray Sum

Total Accepted: 1954 Total Submissions: 8526

Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead.

For example, given the array [2,3,1,2,4,3] and s = 7,
the subarray [4,3] has the minimal length under the problem constraint.

[思路]

两个指针, start end, end向后走,直到 sum 大于 s. 然后start向后, 直到sum 小于s. 同时更新 min值.

[CODE]

public class Solution {
    //1,1,4
    public int minSubArrayLen(int s, int[] nums) {
        //init check
        int start = 0;
        int end = 0;
        
        int sum = 0;
        int min = Integer.MAX_VALUE;
        
        while(start<nums.length && end<nums.length) {
            while(sum<s && end<nums.length) {
                sum += nums[end++];
            }
            while(sum>=s && start<=end) {
                min = Math.min(min, end-start);
                sum -= nums[start++];
            }
        }
        return min==Integer.MAX_VALUE ? 0 : min;
    }
}