LargestRectangleInHistogram
LargestRectangleInHistogram.java 源码
package datastructure.stack.leetcode;
import java.util.*;
/**
* @author roseduan
* @time 2020/11/21 7:55 下午
* @description 柱状图中的最大矩形
*/
public class LargestRectangleInHistogram {
/**
* 暴力法，依次遍历每个柱子查看其高度
*/
public int largestRectangleArea1(int[] heights) {
int max = 0;
for (int i = 0; i < heights.length; i++) {
int min = heights[i];
for (int j = i; j < heights.length; j++) {
min = Math.min(min, heights[j]);
max = Math.max(max, min * (j - i + 1));
}
}
return max;
}
/**
* 使用一个栈
*/
public int largestRectangleArea2(int[] heights) {
Deque<Integer> stack = new ArrayDeque<>(Collections.singletonList(-1));
int max = 0;
for (int i = 0; i < heights.length; i++) {
while (stack.size() > 1 && heights[stack.peekLast()] > heights[i]) {
int n = stack.pollLast();
max = Math.max(max, heights[n] * (i - stack.peekLast() - 1));
}
stack.add(i);
}
if (stack.size() > 1) {
int k = stack.peekLast();
while (stack.size() > 1) {
int n = stack.pollLast();
max = Math.max(max, heights[n] * (k - stack.peekLast()));
}
}
return max;
}
}
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