Solved group anagram / missing number

Author: nhistory

group-anagrams/nhistory.js

@@ -0,0 +1,23 @@
+var groupAnagrams = function (strs) {
+  // Declare hash map to store sorted strs
+  let map = new Map();
+
+  for (let str of strs) {
+    // Sorted each str
+    const sortedStr = str.split("").sort().join("");
+
+    // If there is alread sortedStr on the map, pushed str
+    if (map.has(sortedStr)) {
+      map.get(sortedStr).push(str);
+    } else {
+      // If there is no sortedStr on the map, insert [str]
+      map.set(sortedStr, [str]);
+    }
+  }
+  return Array.from(map.values());
+};
+
+// TC: O(n*klogk)
+// SC: O(n*k)
+// n -> length of strs array
+// k -> amount of character for each element

missing-number/nhistory.js

@@ -0,0 +1,16 @@
+var missingNumber = function (nums) {
+  // Get a expected summation
+  const n = nums.length;
+  const expectedSum = (n * (n + 1)) / 2;
+
+  // Calculate summation of nums
+  let numsSum = 0;
+  for (let i = 0; i < n; i++) {
+    numsSum += nums[i];
+  }
+
+  return expectedSum - numsSum;
+};
+
+// TC: O(n)
+// SC: O(1)