Leetcode-930 Binary Subarrays With Sum(和相同的二元子数组)

class Solution
{
    public:
        int numSubarraysWithSum(vector<int>& A, int S)
        {
            if(S==0)
            {
                int result = 0;
                int count = 0;
                for(int i = 0; i < A.size(); i ++)
                {
                    if(A[i]==0)
                        count ++;
                    else
                    {
                        result += (count+1)*count/2;
                        count = 0;
                    }
                }
                if(count)
                {
                    result += (count+1)*count/2;
                    count = 0;
                }
                return result;
            }
            int totalResult = 0;

            int left = 0,right = 0;
            int oneSum = 0;
            int result = 0;
            for(; right < A.size(); right ++)
            {
                if(oneSum < S)
                {
                    if(A[right]==1)
                        oneSum ++;
                }
                if(oneSum == S)
                {
                    int leftResult = 1,rightResult = 1;
                    while(right != A.size()-1 && A[right+1]==0)
                    {
                        right ++;
                        rightResult ++;
                    }
                    if(A[left]==1)
                        ;
                    else
                    {
                        while(left < right && A[left+1]==0)
                        {
                            left ++;
                            leftResult ++;
                        }
                        left ++;
                        leftResult ++;
                    }
                    result += leftResult*rightResult;
                    left ++;
                    oneSum --;
                }
            }
            return result;
        }
};