reverse
diff --git a/‎src/0042.Trapping-Rain-Water/Solution.go
Lines changed: 40 additions & 1 deletion b/‎src/0042.Trapping-Rain-Water/Solution.go
Lines changed: 40 additions & 1 deletion
diff --git a/‎src/0042.Trapping-Rain-Water/Solution_test.go
Lines changed: 9 additions & 10 deletions b/‎src/0042.Trapping-Rain-Water/Solution_test.go
Lines changed: 9 additions & 10 deletions
@@ -1,5 +1,44 @@
 package Solution
 
-func Solution(x bool) bool {
+import "fmt"
+
+// 三次线性扫描
+func trap(height []int) int {
+	if len(height) == 0 {
+		return 0
+	}
+
+	n, ans := len(height), 0
+	leftMax, rightMax := make([]int, n), make([]int, n)
+
+	//	求第i个矩形左边最高矩形的高度
+	leftMax[0] = height[0]
+	for i := 1; i < n; i++ {
+		leftMax[i] = max(leftMax[i-1], height[i])
+	}
+	//	求第i个矩形右边最高矩形的高度
+	rightMax[n-1] = height[n-1]
+	for i := n - 2; i >= 0; i-- {
+		rightMax[i] = max(rightMax[i+1], height[i])
+	}
+
+	for i := 0; i < n; i++ {
+		fmt.Println(i, leftMax[i], rightMax[i], height[i])
+		ans += min(leftMax[i], rightMax[i]) - height[i]
+	}
+
+	return ans
+}
+
+func max(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}
+func min(x, y int) int {
+	if x > y {
+		return y
+	}
 	return x
 }
@@ -2,28 +2,27 @@ package Solution
 
 import (
 	"reflect"
+	"strconv"
 	"testing"
 )
 
 func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs []int
+		expect int
 	}{
-		{"TestCacse 1", true, true},
-		{"TestCacse 1", true, true},
-		{"TestCacse 1", false, false},
+		{"TestCase", []int{0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1}, 6},
 	}
 
 	//	开始测试
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			ret := Solution(c.inputs)
-			if !reflect.DeepEqual(ret, c.expect) {
+	for i, c := range cases {
+		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
+			got := trap(c.inputs)
+			if !reflect.DeepEqual(got, c.expect) {
 				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, ret, c.inputs)
+					c.expect, got, c.inputs)
 			}
 		})
 	}