c语言直方图最大矩形面积,【算直方图最大矩形面积】了解即可

For example, package go.jacob.day702; import java.util.Stack; public class Demo2 { /* * Runtime: 24 ms.Your runtime beats 67.12 % of java submissions. */ public int largestRectangleArea(int[] heights) { if (heights == null || heights.length < 1) return 0; Stack stack = new Stack(); stack.push(-1); int max = 0; for (int i = 0; i < heights.length; i++) { // 把堆栈中比heights[i]大的元素都pop出，并计算面积 while (stack.peek() != -1 && heights[i] < heights[stack.peek()]) { int top = stack.pop(); // 面积计算公式：(i - 1-stack.peek() ) * heights[top]) max = Math.max(max, (i - 1 - stack.peek()) * heights[top]); } stack.push(i); } while (stack.peek() != -1) { int top = stack.pop(); max = Math.max(max, (heights.length - 1 - stack.peek()) * heights[top]); } return max; } }

把每一行作为x轴起点，看成求直方图中最大矩形面积问题 public int maximalRectangle(char[][] matrix) { if (matrix == null || matrix.length == 0 || matrix[0].length == 0) return 0; int m = matrix.length, n = matrix[0].length; int max = 0; int[] h = new int[n]; for (int i = 0; i < m; i++) { Stack stack = new Stack(); stack.push(-1); for (int j = 0; j < n; j++) { if (matrix[i][j] == '1') h[j] += 1; else h[j] = 0; } for (int j = 0; j < n; j++) { while (stack.peek() != -1 && h[j] < h[stack.peek()]) { int top = stack.pop(); max = Math.max(max, (j - 1 - stack.peek()) * h[top]); } stack.push(j); } while (stack.peek() != -1) { int top = stack.pop(); max = Math.max(max, (n - 1 - stack.peek()) * h[top]); } } return max; }