Merge pull request youngyangyang04#892 from baici1/master

增加42接雨水 go版本的动态规划解法

problems/0042.接雨水.md

@@ -601,7 +601,48 @@ func trap(height []int) int {
 }
 ```
 
+动态规划解法：
+
+```go
+func trap(height []int) int {
+    sum:=0
+    n:=len(height)
+    lh:=make([]int,n)
+    rh:=make([]int,n)
+    lh[0]=height[0]
+    rh[n-1]=height[n-1]
+    for i:=1;i<n;i++{
+        lh[i]=max(lh[i-1],height[i])
+    }
+    for i:=n-2;i>=0;i--{
+        rh[i]=max(rh[i+1],height[i])
+    }
+    for i:=1;i<n-1;i++{
+        h:=min(rh[i],lh[i])-height[i]
+        if h>0{
+            sum+=h
+        }
+    }
+    return sum
+}
+func max(a,b int)int{
+    if a>b{
+        return a
+    }
+    return b
+}
+func min(a,b int)int{
+    if a<b{
+        return a
+    }
+    return b
+}
+```
+
+
+
 JavaScript:
+
 ```javascript
 //双指针
 var trap = function(height) {