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;
}
}