Add solution #93

Author: JoshCrozier

README.md

@@ -73,6 +73,7 @@
 83|[Remove Duplicates from Sorted List](./0083-remove-duplicates-from-sorted-list.js)|Easy|
 88|[Merge Sorted Array](./0088-merge-sorted-array.js)|Easy|
 90|[Subsets II](./0090-subsets-ii.js)|Medium|
+93|[Restore IP Addresses](./0093-restore-ip-addresses.js)|Medium|
 94|[Binary Tree Inorder Traversal](./0094-binary-tree-inorder-traversal.js)|Easy|
 98|[Validate Binary Search Tree](./0098-validate-binary-search-tree.js)|Medium|
 100|[Same Tree](./0100-same-tree.js)|Easy|

solutions/0093-restore-ip-addresses.js

@@ -0,0 +1,42 @@
+/**
+ * 93. Restore IP Addresses
+ * https://leetcode.com/problems/restore-ip-addresses/
+ * Difficulty: Medium
+ *
+ * A valid IP address consists of exactly four integers separated by single
+ * dots. Each integer is between 0 and 255 (inclusive) and cannot have
+ * leading zeros.
+ *
+ * For example, "0.1.2.201" and "192.168.1.1" are valid IP addresses, but
+ * "0.011.255.245", "192.168.1.312" and "[email protected]" are invalid IP addresses.
+ *
+ * Given a string s containing only digits, return all possible valid IP
+ * addresses that can be formed by inserting dots into s. You are not allowed
+ * to reorder or remove any digits in s. You may return the valid IP addresses
+ * in any order.
+ */
+
+/**
+ * @param {string} s
+ * @return {string[]}
+ */
+var restoreIpAddresses = function(s) {
+  return backtrack([], s);
+};
+
+function backtrack(order, string, result = []) {
+  const isValid = s => +s <= 255 && `${+s}` === s;
+
+  if (order.length === 3 && isValid(string)) {
+    result.push([...order, string].join('.'));
+  } else {
+    for (let index = 1; index < 4; index++) {
+      const sliced = string.slice(0, index);
+      if (isValid(sliced)) {
+        backtrack([...order, sliced], string.slice(index), result);
+      }
+    }
+  }
+
+  return result;
+}