[LeetCode] Maximal Rectangle

[LeetCode] Maximal Rectangle

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

Dynamic Planning

Use the left [] array to record the 1 distance from this point to the leftmost (inside the rectangle), and use the right [] array to record the 1 distance from this point to the rightmost (inside the rectangle, height [] records the maximum height of 1 in the rectangle of the vertex.

public class Solution {public int maximalRectangle(char[][] matrix) {if (matrix.length == 0)return 0;int row = matrix.length;int column = matrix[0].length;int left[] = new int[column], right[] = new int[column], height[] = new int[column];Arrays.fill(right, column-1);int res = 0;for (int i = 0; i < row; i++) {int l = 0, r = column - 1;for (int j = 0; j < column; j++) {if (matrix[i][j] == '1') {left[j] = Math.max(left[j], l);height[j]++;} else {l = j+1;left[j] =0;height[j] = 0;right[j] = column - 1;}}for (int j = column - 1; j >= 0; j--) {if (matrix[i][j] == '1') {right[j] = Math.min(r, right[j]);res = Math.max(res, height[j] * (right[j] - left[j]+1));} else {r = j-1;}}}return res;}}