93. 复原 IP 地址

Author: w2xi

README.md

@@ -48,6 +48,7 @@
 |82|[删除排序链表中的重复元素 II](https://leetcode.cn/problems/remove-duplicates-from-sorted-list-ii/)|[JavaScript](./algorithms/remove-duplicates-from-sorted-list-ii.js)|Medium|
 |83|[删除排序链表中的重复元素](https://leetcode.cn/problems/remove-duplicates-from-sorted-list/)|[JavaScript](./algorithms/remove-duplicates-from-sorted-list.js)|Easy|
 |88|[合并两个有序数组](https://leetcode.cn/problems/merge-sorted-array/)|[JavaScript](./algorithms/merge-sorted-array.js)|Easy|
+|93|[复原 IP 地址](https://leetcode.cn/problems/restore-ip-addresses/)|[JavaScript](./algorithms/restore-ip-addresses.js)|Medium|
 |94|[二叉树的中序遍历](https://leetcode.cn/problems/binary-tree-inorder-traversal/)|[JavaScript](./algorithms/binary-tree-inorder-traversal.js)|Easy|
 |98|[验证二叉搜索树](https://leetcode.cn/problems/validate-binary-search-tree/)|[JavaScript](./algorithms/validate-binary-search-tree.js)|Medium|
 |100|[相同的树](https://leetcode.cn/problems/same-tree/)|[JavaScript](./algorithms/same-tree.js)|Easy|

algorithms/restore-ip-addresses.js

@@ -0,0 +1,34 @@
+/**
+ * 93. 复原 IP 地址
+ * @param {string} s
+ * @return {string[]}
+ */
+var restoreIpAddresses = function (s) {
+  const result = [];
+  const path = [];
+
+  const backtracking = (s, startIndex = 0) => {
+    if (path.length === 4) {
+      if (startIndex === s.length) {
+        result.push(path.join("."));
+      }
+      return;
+    }
+    for (let i = startIndex; i < s.length; i++) {
+      const str = s.slice(startIndex, i + 1);
+      if (str.length >= 3 && str > 255) {
+        break;
+      }
+      if (str.length > 1 && str[0] === "0") {
+        // 排除前导0
+        break;
+      }
+      path.push(str);
+      backtracking(s, i + 1);
+      path.pop();
+    }
+  };
+  backtracking(s);
+
+  return result;
+};