Added valid anagram solution

Author: nhistory

valid-anagram/nhistory.js

@@ -0,0 +1,36 @@
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {boolean}
+ */
+var isAnagram = function (s, t) {
+  /*
+    // Split string and sort charaters
+    // Compare s and t after sorting
+    return s.split("").sort().join() === t.split("").sort().join()
+    // 92ms, 53.29MB
+    */
+
+  // Made Hashmap and count number of each charater
+  let map = {};
+
+  // Check character length between s and t
+  if (s.length !== t.length) return false;
+  // Put a character and add or substract number
+  for (let i = 0; i < s.length; i++) {
+    map[s[i]] = map[s[i]] ? map[s[i]] + 1 : 1;
+    map[t[i]] = map[t[i]] ? map[t[i]] - 1 : -1;
+  }
+
+  for (let i = 0; i < s.length; i++) {
+    if (map[s[i]] !== 0) return false;
+  }
+
+  return true;
+};
+
+console.log(isAnagram("anagram", "nagaram"));
+console.log(isAnagram("rat", "car"));
+
+// TC: O(n)
+// SC: O(n)