Merge pull request youngyangyang04#1010 from xiaofei-2020/ts6

添加（面试题02.07.链表相交.md）：增加typescript版本

Author: youngyangyang04

problems/面试题02.07.链表相交.md

@@ -239,6 +239,43 @@ var getIntersectionNode = function(headA, headB) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function getIntersectionNode(headA: ListNode | null, headB: ListNode | null): ListNode | null {
+  let sizeA: number = 0,
+    sizeB: number = 0;
+  let curA: ListNode | null = headA,
+    curB: ListNode | null = headB;
+  while (curA) {
+    sizeA++;
+    curA = curA.next;
+  }
+  while (curB) {
+    sizeB++;
+    curB = curB.next;
+  }
+  curA = headA;
+  curB = headB;
+  if (sizeA < sizeB) {
+    [sizeA, sizeB] = [sizeB, sizeA];
+    [curA, curB] = [curB, curA];
+  }
+  let gap = sizeA - sizeB;
+  while (gap-- && curA) {
+    curA = curA.next;
+  }
+  while (curA && curB) {
+    if (curA === curB) {
+      return curA;
+    }
+    curA = curA.next;
+    curB = curB.next;
+  }
+  return null;
+};
+```
+
 C：
 
 ```c