85. Maximal Rectangle 发表于 2022-05-24 Violence1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556class Solution { public int maximalRectangle(char[][] matrix) { int m = matrix.length, n = matrix[0].length; int[][] tallMatrix = new int[m][n]; for (int j = 0; j < n; j++) { tallMatrix[0][j] = matrix[0][j] == '1' ? 1 : 0; } for (int i = 1; i < m; i++) { for (int j = 0; j < n; j++) { if (matrix[i][j] == '1') { if (matrix[i - 1][j] == '1') { tallMatrix[i][j] = tallMatrix[i - 1][j] + 1; } else { tallMatrix[i][j] = 1; } } } } int maxArea = 0; for (int i = 0; i < m; i++) { for (int j = 0; j < n; j++) { if (tallMatrix[i][j] == 0) { continue; } if (tallMatrix[i][j] * n <= maxArea) { continue; } // 寻找左右侧高度大于等于当前柱子的所有柱子 int width = 1; // self for (int k = j - 1; k >= 0; k--) { if (tallMatrix[i][k] >= tallMatrix[i][j]) { width++; } else { break; } } for (int k = j + 1; k < n; k++) { if (tallMatrix[i][k] >= tallMatrix[i][j]) { width++; } else { break; } } maxArea = Math.max(maxArea, width * tallMatrix[i][j]); } } return maxArea; }} Stack1234567891011121314151617181920212223242526272829303132333435class Solution { public int maximalRectangle(char[][] matrix) { int m = matrix.length, n = matrix[0].length; int maxArea = 0; int[] heights = new int[n + 2]; for (int rowIndex = 0; rowIndex < m; rowIndex++) { for (int colIndex = 0; colIndex < n; colIndex++) { heights[colIndex + 1] = matrix[rowIndex][colIndex] == '1' ? 1 + heights[colIndex + 1] : 0; } maxArea = Math.max(maxArea, maximalRectangle(heights)); } return maxArea; } private int maximalRectangle(int[] heights) { int maxArea = 0; Stack<Integer> increaseStack = new Stack<>(); for (int i = 0; i < heights.length; i++) { while (!increaseStack.isEmpty() && heights[i] < heights[increaseStack.peek()]) { int height = heights[increaseStack.pop()]; int leftIndex = increaseStack.peek(); // exclusive int rightIndex = i; // exclusive int width = rightIndex - leftIndex - 1; maxArea = Math.max(maxArea, height * width); } increaseStack.push(i); } return maxArea; }} Reference85. Maximal Rectangle