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.
解题思路:
用一个指针维护左边界即可,JAVA实现如下:
public int minSubArrayLen(int s, int[] nums) {
if(nums==null||nums.length==0)
return 0;
int left=0,sum=0,min=Integer.MAX_VALUE;
for(int i=0;i<nums.length;i++){
sum+=nums[i];
while(sum>=s){
min=Math.min(min, i-left+1);
sum-=nums[left++];
}
}
return min==Integer.MAX_VALUE?0:min;
}