Merge pull request #1108 from xiaofei-2020/tree25

添加（530.二叉搜索树的最小绝对差）：增加typescript版本

problems/0530.二叉搜索树的最小绝对差.md

@@ -364,5 +364,74 @@ var getMinimumDifference = function(root) {
 }
 ```
 
+## TypeScript
+
+> 辅助数组解决
+
+```typescript
+function getMinimumDifference(root: TreeNode | null): number {
+    let helperArr: number[] = [];
+    function recur(root: TreeNode | null): void {
+        if (root === null) return;
+        recur(root.left);
+        helperArr.push(root.val);
+        recur(root.right);
+    }
+    recur(root);
+    let resMin: number = Infinity;
+    for (let i = 0, length = helperArr.length; i < length - 1; i++) {
+        resMin = Math.min(resMin, helperArr[i + 1] - helperArr[i]);
+    }
+    return resMin;
+};
+```
+
+> 递归中解决
+
+```typescript
+function getMinimumDifference(root: TreeNode | null): number {
+    let preNode: TreeNode | null= null;
+    let resMin: number = Infinity;
+    function recur(root: TreeNode | null): void {
+        if (root === null) return;
+        recur(root.left);
+        if (preNode !== null) {
+            resMin = Math.min(resMin, root.val - preNode.val);
+        }
+        preNode = root;
+        recur(root.right);
+    }
+    recur(root);
+    return resMin;
+};
+```
+
+> 迭代法-中序遍历
+
+```typescript
+function getMinimumDifference(root: TreeNode | null): number {
+    const helperStack: TreeNode[] = [];
+    let curNode: TreeNode | null = root;
+    let resMin: number = Infinity;
+    let preNode: TreeNode | null = null;
+    while (curNode !== null || helperStack.length > 0) {
+        if (curNode !== null) {
+            helperStack.push(curNode);
+            curNode = curNode.left;
+        } else {
+            curNode = helperStack.pop()!;
+            if (preNode !== null) {
+                resMin = Math.min(resMin, curNode.val - preNode.val);
+            }
+            preNode = curNode;
+            curNode = curNode.right;
+        }
+    }
+    return resMin;
+};
+```
+
+
+
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