1 public class Solution { 2     public int maximalRectangle(char[][] matrix) { 3         int row = matrix.length; 4         if(row == 0) return 0; 5         int col = matrix[0].length; 6         if(col == 0) return 0; 7          8         int maxArea = 0; 9         10         for(int i = 0; i < row; i++){11             int[] height = new int[col];12             for(int j = 0; j < col; j++){13                 if(matrix[i][j] == ‘1‘){14                     for(int k = i; k >=0; k--){15                         if(matrix[k][j] == ‘1‘){16                             height[j]++;17                         }18                         else break;19                     }20                 }21             }22             maxArea = Math.max(maxArea, largestRectangleArea(height));23         }24         25         return maxArea;26     }27     28     public int largestRectangleArea(int[] height) {29         int len = height.length;30         Stack<Integer> s = new Stack<Integer>();31         int maxArea = 0;32         for(int i = 0; i <= len; i++){33             int h = (i == len ? 0 : height[i]);34             if(s.isEmpty() || h >= height[s.peek()]){35                 s.push(i);36             }else{37                 int tp = s.pop();38                 maxArea = Math.max(maxArea, height[tp] * (s.isEmpty() ? i : i - 1 - s.peek()));39                 i--;40             }41         }42         return maxArea;43     }44 }