Leetcode-934 Shortest Bridge(最短的桥)

class Solution
{
    private:
        vector<pair<int,int>> graphA,graphB;
        int colSize;
        int mark;
        const int xList[4] {1,0,0,-1};
        const int yList[4] {0,1,-1,0};
    public:
        bool isValid(int x,int y)
        {
            return (x<colSize && y<colSize && x>=0 && y >= 0);
        }
        void floodFill(vector<vector<int>>& A,int x,int y)
        {
            A[x][y] = mark;
            if(mark == 2)
            {
                graphA.push_back({x,y});
            }
            else
            {
                graphB.push_back({x,y});
            }
            for(int i = 0;i < 4;i ++)
            {
                int newX = x+xList[i];
                int newY = y+yList[i];
                if(isValid(newX,newY) && A[newX][newY] == 1)
                {
                    floodFill(A,newX,newY);
                }
            }
        }
        int shortestBridge(vector<vector<int>>& A)
        {
            colSize = A.size();
            mark = 2;
            for(int i = 0;i < A.size();i ++)
            {
                for(int j = 0;j < A[i].size();j ++)
                {
                    if(A[i][j] == 1)
                    {
                        floodFill(A,i,j);
                        mark ++;
                    }
                } 
            }

            int result = 3939;
            for(auto p1:graphA)
            {
                for(auto p2:graphB)
                {
                    if(abs(p1.first-p2.first)+abs(p1.second-p2.second) < result)
                    {
                        result = abs(p1.first-p2.first)+abs(p1.second-p2.second);
                    }
                }
            }
            return result-1;
        }
};