add new solutions

solutions/1/q102/solution.go

@@ -0,0 +1,43 @@
+package q102
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func levelOrder(root *TreeNode) [][]int {
+	if root == nil {
+		return [][]int{}
+	}
+	ret := [][]int{}
+
+	type qElem struct {
+		lvl  int
+		node *TreeNode
+	}
+	curLvl := 0
+	curLvlNodes := []int{}
+	queue := []qElem{{0, root}}
+	for ; len(queue) > 0; queue = queue[1:] {
+		cur := &queue[0]
+		if cur.lvl != curLvl {
+			ret = append(ret, curLvlNodes)
+			curLvlNodes = []int{cur.node.Val}
+			curLvl = cur.lvl
+		} else {
+			curLvlNodes = append(curLvlNodes, cur.node.Val)
+		}
+		if cur.node.Left != nil {
+			queue = append(queue, qElem{lvl: cur.lvl + 1, node: cur.node.Left})
+		}
+		if cur.node.Right != nil {
+			queue = append(queue, qElem{lvl: cur.lvl + 1, node: cur.node.Right})
+		}
+	}
+
+	ret = append(ret, curLvlNodes)
+	return ret
+}
+
+var _ = levelOrder