參考標準解法，主要是用的DFS的解法。 這裏有個坑就是在更新i,j的時候，要用tmpi。
class Solution {
private:
vector<int> x{-1, 1, 0, 0};
vector<int> y{0, 0, 1, -1};
public:
int numIslands(vector<vector<char>>& grid) {
if(!grid.size()) return 0;
int size_x = grid.size();
int size_y = grid[0].size();
//cout << "size_x is:" << size_x << "size_y is:" << size_y;
int islandCount = 0;
//vector<vector<int>> mark(size_x, vector<int>(size_y,0));
for(int i = 0; i < size_x; i++){
for(int j = 0; j < size_y; j++){
if(grid[i][j] == '1'){
cout << endl << "found i is" << i << "found j is" << j << endl;
islandCount++;
DFS(grid, i, j);
}
}
}
return islandCount;
}
void DFS(vector<vector<char>>& grid, int i, int j){
if(grid[i][j]!='1') { // 訪問過直接返回
return;
}
grid[i][j] = '0'; //
for(int k = 0; k < 4 ; k++){
int tmpi = i + x[k];
int tmpj = j + y[k];
if( tmpi < 0 || tmpi >= grid.size() || tmpj < 0 || tmpj >= grid[0].size()) continue;
if(grid[tmpi][tmpj] == '1') DFS(grid, tmpi, tmpj);
}
}
};