209. 长度最小的子数组C

滑动窗口的妙用！！

int minSubArrayLen(int target, int* nums, int numsSize) {
    int sum=nums[0];//区间head到tail的和
    int head=0,tail=0;
    int minn=numsSize;
    int tag=0;
    if(numsSize==0) return -1;
    while(head<=tail && tail<numsSize){
        if(sum<target ){
            tail++;
            if(tail==numsSize) break;
            sum+=nums[tail];
        }else if(sum>=target ){
            tag=1;
            if(minn>(tail-head+1)) minn=tail-head+1;
            sum-=nums[head++];
        }
    }
    if(tag==0){
        return 0;
    }
    return minn;
}

结果：