[LeetCode] Surrounded Regions 广度搜索

#include <vector>
#include <iostream>
#include <iterator>
using namespace std;

class Solution {
public:
    void solve(vector<vector<char> > &board) {
        int m=board.size();
        if(m<2) return;
        int n=board[0].size();
        if(n<2) return;
        vector<vector<bool> > flag;
        for(int i=0;i<m;i++)    flag.push_back(vector<bool>(n,false));
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                if(board[i][j]==‘X‘)    flag[i][j]=true;
                if(board[i][j]==‘O‘&&flag[i][j]==false)
                    help_f(i,j,board,flag);
            }
        }
        return ;
    }
    void help_f(int i,int j,vector<vector<char> > &board,vector<vector<bool> > &flag)
    {
//        cout<<"Azhu"<<endl;
        vector<pair<int,int> > tmp;
        tmp.push_back({i,j});
        flag[i][j]=true;
        int now_idx=0,m=board.size(),n=board[0].size();
        while(now_idx<tmp.size()){
            int now_i = tmp[now_idx].first,now_j = tmp[now_idx].second;
            if(now_i-1>=0&&board[now_i-1][now_j]==‘O‘&&flag[now_i-1][now_j]==false){
                tmp.push_back({now_i-1,now_j});
                flag[now_i-1][now_j]=true;
            }
            if(now_i+1<m&&board[now_i+1][now_j]==‘O‘&&flag[now_i+1][now_j]==false){
                tmp.push_back({now_i+1,now_j});
                flag[now_i+1][now_j]=true;
            }
            if(now_j-1>=0&&board[now_i][now_j-1]==‘O‘&&flag[now_i][now_j-1]==false){
                tmp.push_back({now_i,now_j-1});
                flag[now_i][now_j-1]=true;
            }
            if(now_j+1<n&&board[now_i][now_j+1]==‘O‘&&flag[now_i][now_j+1]==false){
                tmp.push_back({now_i,now_j+1});
                flag[now_i][now_j+1]=true;
            }
            now_idx++;
        }
        bool canCapture=true;
        now_idx=0;
        while(canCapture&&now_idx<tmp.size()){
            int now_i = tmp[now_idx].first,now_j = tmp[now_idx].second;
            if(now_i==0||now_i==m-1||now_j==0||now_j==n-1)  canCapture=false;
            now_idx++;
        }
        if(canCapture){
            now_idx=0;
            while(now_idx<tmp.size()){
                int now_i = tmp[now_idx].first,now_j = tmp[now_idx].second;
                board[now_i][now_j]=‘X‘;
                now_idx++;
            }
        }
        return ;
    }
};

int main()
{
    vector<vector<char> > board{
        {{‘X‘,‘X‘,‘X‘,‘O‘}},
        {{‘X‘,‘O‘,‘O‘,‘X‘}},
        {{‘X‘,‘X‘,‘X‘,‘X‘}},
        {{‘X‘,‘O‘,‘O‘,‘X‘}}
    };
    Solution sol;
    sol.solve(board);
    for(int i=0;i<board.size();i++){
        copy(board[i].begin(),board[i].end(),ostream_iterator<char>(cout," "));
        cout<<endl;
    }

    return 0;
}