[leedcode 209] Minimum Size Subarray Sum

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.

public class Solution {
public int minSubArrayLen(int s, int[] nums) {
//借助一个指针start，判断从start到i的sum是否大于s，如果大于，start++，并且不断更新minLen
//注意，一开始需要将minLen初始化为Integer.MAX_VALUE
int minLen=Integer.MAX_VALUE;
int start=0;
int sum=0;
for(int i=0;i<nums.length;i++){
sum+=nums[i];
while(sum>=s){
minLen=Math.min(minLen,i-start+1);
sum-=nums[start];
start++;

}
}
return minLen==Integer.MAX_VALUE?0:minLen;
}
}