From 419b1940e55651cb034b717b067297a6922d2ead Mon Sep 17 00:00:00 2001
From: Kohei Asai <me@axross.io>
Date: Sun, 29 Sep 2019 20:50:29 -0700
Subject: [PATCH] 169. Majority Element

---
 solutions/majorityElement.test.ts | 11 +++++++++++
 solutions/majorityElement.ts      | 15 +++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 solutions/majorityElement.test.ts
 create mode 100644 solutions/majorityElement.ts

diff --git a/solutions/majorityElement.test.ts b/solutions/majorityElement.test.ts
new file mode 100644
index 0000000..6d23ea1
--- /dev/null
+++ b/solutions/majorityElement.test.ts
@@ -0,0 +1,11 @@
+import majorityElement from "./majorityElement";
+
+describe("169. Majority Element", () => {
+  const TEST_CASES = new Map([[[3, 2, 3], 3], [[2, 2, 1, 1, 1, 2, 2], 2]]);
+
+  for (const [nums, expected] of TEST_CASES) {
+    it(`returns ${expected} when calling with [${nums}]`, () => {
+      expect(majorityElement(nums)).toBe(expected);
+    });
+  }
+});
diff --git a/solutions/majorityElement.ts b/solutions/majorityElement.ts
new file mode 100644
index 0000000..fed4839
--- /dev/null
+++ b/solutions/majorityElement.ts
@@ -0,0 +1,15 @@
+// 169. Majority Element
+// https://leetcode.com/problems/majority-element/
+export default function majorityElement(nums: number[]): number {
+  const counts = new Map();
+
+  for (const num of nums) {
+    const count = (counts.get(num) || 0) + 1;
+
+    if (count >= nums.length / 2) return num;
+
+    counts.set(num, count);
+  }
+
+  throw new Error();
+}