Add solution #97

Author: JoshCrozier

README.md

@@ -99,6 +99,7 @@
 94|[Binary Tree Inorder Traversal](./0094-binary-tree-inorder-traversal.js)|Easy|
 95|[Unique Binary Search Trees II](./0095-unique-binary-search-trees-ii.js)|Medium|
 96|[Unique Binary Search Trees](./0096-unique-binary-search-trees.js)|Medium|
+97|[Interleaving String](./0097-interleaving-string.js)|Medium|
 98|[Validate Binary Search Tree](./0098-validate-binary-search-tree.js)|Medium|
 99|[Recover Binary Search Tree](./0099-recover-binary-search-tree.js)|Medium|
 100|[Same Tree](./0100-same-tree.js)|Easy|

solutions/0097-interleaving-string.js

@@ -0,0 +1,39 @@
+/**
+ * 97. Interleaving String
+ * https://leetcode.com/problems/interleaving-string/
+ * Difficulty: Medium
+ *
+ * Given strings s1, s2, and s3, find whether s3 is formed by an interleaving of s1 and s2.
+ *
+ * An interleaving of two strings s and t is a configuration where s and t are divided into
+ * n and m substrings respectively, such that:
+ * - s = s1 + s2 + ... + sn
+ * - t = t1 + t2 + ... + tm
+ * - |n - m| <= 1
+ * - The interleaving is s1 + t1 + s2 + t2 + s3 + t3 + ... or t1 + s1 + t2 + s2 + t3 + s3 + ...
+ *
+ * Note: a + b is the concatenation of strings a and b.
+ */
+
+/**
+ * @param {string} s1
+ * @param {string} s2
+ * @param {string} s3
+ * @return {boolean}
+ */
+var isInterleave = function(s1, s2, s3) {
+  const values = new Array(s1.length + 1).fill().map(() => []);
+
+  if (s1.length + s2.length !== s3.length) {
+    return false;
+  }
+
+  for (let i = 0; i <= s1.length; i++) {
+    for (let j = 0; j <= s2.length; j++) {
+      values[i][j] = i && values[i - 1][j] && s3[i + j - 1] === s1[i - 1]
+        || j && values[i][j - 1] && s3[i + j - 1] === s2[j - 1] || !i && !j;
+    }
+  }
+
+  return Boolean(values.pop().pop());
+};