Create: 42-Trapping-Rain-Water.go

go/42-Trapping-Rain-Water.go

@@ -0,0 +1,30 @@
+func trap(height []int) int {
+ if height == nil {
+ return 0
+ }
+
+ left, right := 0, len(height) - 1
+ leftMax, rightMax := height[left], height[right]
+ res := 0
+
+ for left < right {
+ if leftMax < rightMax {
+ left += 1
+ leftMax = max(leftMax, height[left])
+ res += leftMax - height[left]
+ } else {
+ right -= 1
+ rightMax = max(rightMax, height[right])
+ res += rightMax - height[right]
+ }
+ }
+ return res
+}
+
+// Golang does not have a built-in max for integers
+func max(a int, b int) int {
+ if a > b {
+ return a;
+ }
+ return b;
+}