LeetCode OJ：Maximal Square（最大矩形）

Given a 2D binary matrix filled with 0's and 1's, find the largest square containing all 1's and return its area.

For example, given the following matrix:

1 0 1 0 0
1 0 1 1 1
1 1 1 1 1
1 0 0 1 0

在给定的二维字符数组，找出最大全为1的矩形包含的1的个数：

注意这里相当于求面积而已，只要求出边长就很好办了。边长用dp很好求，这题其实跟前面有道dp问题很像，以后有时间找出来，先贴下代码：

 class Solution {
 public:
     int maximalSquare(vector<vector<char>>& matrix) {
         if(!matrix.size()||!matrix[].size()) return ;
         vector<vector<int>>dp(matrix.size(), vector<int>(matrix[].size(), ));
         int maxVal = ;
         for(int i = ; i < matrix.size(); ++i){
             if(matrix[i][] == ''){
                 dp[i][] = ;
                 maxVal = ;
             }else dp[i][] = ;
         }
         for(int j = ; j < matrix[].size(); ++j){
             if(matrix[][j] == ''){
                 dp[][j] = ;
                 maxVal = ;
             }else dp[][j] = ;
         }
         for(int i = ; i < matrix.size(); ++i){
             for(int j = ; j < matrix[].size(); ++j){
                 if(matrix[i][j] == ''){
                     dp[i][j] = min(dp[i-][j], min(dp[i][j-], dp[i-][j-])) + ;
                     maxVal = max(maxVal, dp[i][j]);
                 }else
                     dp[i][j] = ;
             }
         }
         return maxVal*maxVal;
     }
 };