go: add 0112 Path Sum solution

Author: josuebrunel

go/0112-Path-Sum.go

@@ -0,0 +1,26 @@
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func hasPathSum(root *TreeNode, targetSum int) bool {
+	if root == nil {
+		return false
+	}
+
+	return dfs(root, 0, targetSum)
+}
+
+func dfs(root *TreeNode, curSum, targetSum int) bool {
+	if root == nil {
+		return false
+	}
+	curSum += root.Val
+	if curSum == targetSum && root.Left == nil && root.Right == nil {
+		return true
+	}
+	return dfs(root.Left, curSum, targetSum) || dfs(root.Right, curSum, targetSum)
+}