Careercup - Facebook面试题 - 5998719358992384

2014-05-02 00:22

题目链接

原题：

Given a matrix consisting of 's and 1's, find the largest connected component consisting of 's.

题目：给定一个01矩阵，找出由1构成的连通分量中最大的一个。

解法：四邻接还是八邻接也不说，我就当四邻接了。这种Flood Fill问题，可以用BFS或者DFS解决。

代码：

 // http://www.careercup.com/question?id=5998719358992384
 #include <vector>
 using namespace std;

 class Solution {
 public:
     int maxConnectedComponent(vector<vector<int> > &v) {
         n = (int)v.size();
         if (n == ) {
             return ;
         }
         m = (int)v[].size();
         if (m == ) {
             return ;
         }

         int res, max_res;

         max_res = ;
         for (i = ; i < n; ++i) {
             for (j = ; j < m; ++j) {
                 if (!v[i][j]) {
                     continue;
                 }
                 res = ;

                 v[i][j] = ;
                 ++res;
                 DFS(v, i, j, res);
                 max_res = res > max_res ? res : max_res;
             }
         }

         return max_res;
     };
 private:
     int n, m;

     void DFS(vector<vector<int> > &v, int i, int j, int &res) {
         static const int d[][] = {
             {-,  },
             { , -},
             {+,  },
             { , +}
         };

         int k, x, y;
         for (k = ; k < ; ++k) {
             x = i + d[k][];
             y = j + d[k][];
             if (x <  || x > n -  || y <  || y > m - ) {
                 continue;
             }
             if (!v[x][y]) {
                 continue;
             }
             v[x][y] = ;
             ++res;
             DFS(v, x, y, res);
         }
     };
 };