0094-binary-tree-inorder-traversal.go

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func inorderTraversal(root *TreeNode) []int {
	res := []int{}
	stack := []*TreeNode{}
	cur := root

	for cur != nil || len(stack) > 0 {
		if cur != nil {
			stack = append(stack, cur)
			cur = cur.Left
		} else {
			cur, stack = stack[len(stack)-1], stack[:len(stack)-1]
			res = append(res, cur.Val)
			cur = cur.Right
		}
	}
	return res
}