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MaximalSquare.java
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MaximalSquare.java
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/**
* 221. Maximal Square
* @author LBW
*/
public class MaximalSquare {
public int maximalSquare(char[][] matrix) {
int m = matrix.length, n = matrix[0].length;
int res = 0;
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
int square = findLargestSquare(i, j, m, n, matrix);
res = Math.max(square, res);
}
}
return res;
}
// 往[i, j]的右下方寻找最大的全1方针
private int findLargestSquare(int i, int j, int m, int n, char[][] matrix) {
if (matrix[i][j] == '0')
return 0;
int ring = 1;
boolean flag = true;
while (flag) {
if (i + ring >= m || j + ring >= n) {
flag = false;
break;
}
for (int k = 0; k <= ring; k++) {
if (!(matrix[i + ring][j + k] == '1')) {
flag = false;
break;
}
if (!(matrix[i + k][j + ring] == '1')) {
flag = false;
break;
}
}
if (flag)
ring += 1;
}
return ring * ring;
}
}