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添加（二叉树的统一迭代法.md）：增加typescript版本

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Steve2020
2022-01-26 19:18:23 +08:00
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commit 7ed2a3aef7
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problems/二叉树的统一迭代法.md
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@ -522,7 +522,75 @@ var postorderTraversal = function(root, res = []) {
```
TypeScript：
```typescript
// 前序遍历（迭代法）
function preorderTraversal(root: TreeNode | null): number[] {
let helperStack: (TreeNode | null)[] = [];
let res: number[] = [];
let curNode: TreeNode | null;
if (root === null) return res;
helperStack.push(root);
while (helperStack.length > 0) {
curNode = helperStack.pop()!;
if (curNode !== null) {
if (curNode.right !== null) helperStack.push(curNode.right);
helperStack.push(curNode);
helperStack.push(null);
if (curNode.left !== null) helperStack.push(curNode.left);
} else {
curNode = helperStack.pop()!;
res.push(curNode.val);
}
}
return res;
};
// 中序遍历（迭代法）
function inorderTraversal(root: TreeNode | null): number[] {
let helperStack: (TreeNode | null)[] = [];
let res: number[] = [];
let curNode: TreeNode | null;
if (root === null) return res;
helperStack.push(root);
while (helperStack.length > 0) {
curNode = helperStack.pop()!;
if (curNode !== null) {
if (curNode.right !== null) helperStack.push(curNode.right);
helperStack.push(curNode);
helperStack.push(null);
if (curNode.left !== null) helperStack.push(curNode.left);
} else {
curNode = helperStack.pop()!;
res.push(curNode.val);
}
}
return res;
};
// 后序遍历（迭代法）
function postorderTraversal(root: TreeNode | null): number[] {
let helperStack: (TreeNode | null)[] = [];
let res: number[] = [];
let curNode: TreeNode | null;
if (root === null) return res;
helperStack.push(root);
while (helperStack.length > 0) {
curNode = helperStack.pop()!;
if (curNode !== null) {
if (curNode.right !== null) helperStack.push(curNode.right);
helperStack.push(curNode);
helperStack.push(null);
if (curNode.left !== null) helperStack.push(curNode.left);
} else {
curNode = helperStack.pop()!;
res.push(curNode.val);
}
}
return res;
};
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>