【题目】
Given a 2D binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.
Example:
Input: 1 0 1 0 0 1 0 1 1 1 1 1 1 1 1 1 0 0 1 0 Output: 4
【思路】
- dp square面积和三个有关
- 注意特殊空集条件
【代码】
class Solution { public int maximalSquare(char[][] matrix) { if(matrix.length==0) return 0; int dp[][]=new int[matrix.length+1][matrix[0].length+1]; int ans=0; for(int i=1;i<matrix.length+1;i++){ for(int j=1;j<matrix[0].length+1;j++){ if(matrix[i-1][j-1]=='1'){ dp[i][j]=Math.min(Math.min(dp[i-1][j],dp[i][j-1]),dp[i-1][j-1])+1; ans=Math.max(ans,dp[i][j]); } } } return ans*ans; } }