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top-100-liked/72/leetcode_test.go

@@ -0,0 +1,60 @@
+package top100liked
+
+import (
+	"fmt"
+	"testing"
+)
+
+// https://leetcode.cn/problems/largest-rectangle-in-histogram/?envType=study-plan-v2&envId=top-100-liked
+
+// 暴力法，超时
+// func largestRectangleArea(heights []int) int {
+// 	maxArea := 0
+// 	// i 是每个组合中的元素数量
+// 	for i := 1; i <= len(heights); i++ {
+// 		// j 是在整个 heights 中滑动的次数
+// 		for j := 0; j < len(heights)-i+1; j++ {
+// 			// 计算
+// 			maxArea = max(maxArea, slices.Min(heights[j:j+i])*i)
+// 		}
+// 	}
+// 	return maxArea
+// }
+
+func largestRectangleArea(heights []int) int {
+	stack := []int{}
+	maxArea := 0
+	for i := range len(heights) + 1 {
+		if len(stack) == 0 {
+			stack = append(stack, i)
+			continue
+		}
+		var cur int
+		if i == len(heights) {
+			cur = 0
+		} else {
+			cur = heights[i]
+		}
+		if cur >= heights[stack[len(stack)-1]] {
+			stack = append(stack, i)
+		} else {
+			for len(stack) > 0 && heights[stack[len(stack)-1]] > cur {
+				top := stack[len(stack)-1]
+				stack = stack[:len(stack)-1]
+				width := i
+				if len(stack) > 0 {
+					width = i - stack[len(stack)-1] - 1
+				}
+				maxArea = max(maxArea, heights[top]*width)
+			}
+			stack = append(stack, i)
+		}
+	}
+	return maxArea
+}
+
+func Test(t *testing.T) {
+	fmt.Println(largestRectangleArea([]int{2, 1, 5, 6, 2, 3}))
+	fmt.Println(largestRectangleArea([]int{1}))
+	fmt.Println(largestRectangleArea([]int{2, 1, 2}))
+}