From 08e310e19daa6c973eb0db1ae5ea23a002ac0f47 Mon Sep 17 00:00:00 2001
From: Lam Haoyin <root@eatswap.org>
Date: Sun, 2 Jan 2022 11:28:22 +0800
Subject: [PATCH] feat: usage of __builtin_clz

---
 2201/220102-CN.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/2201/220102-CN.cpp b/2201/220102-CN.cpp
index e4d3225..edb5c01 100644
--- a/2201/220102-CN.cpp
+++ b/2201/220102-CN.cpp
@@ -4,8 +4,9 @@ class Solution {
 public:
 	// O(log(n))
 	static int lastRemaining(int n) {
-		int cnt = 0, ret = 1;
-		for (int i = n; i >>= 1; ++cnt);
+		// int cnt = 0, ret = 1;
+		int ret = 1, cnt = __builtin_clz(n) ^ 31;
+		// for (int i = n; i >>= 1; ++cnt);
 		for (int i = 0; i < cnt; ++i, n >>= 1)
 			ret += !(1 & i) || (1 & n) ? (1 << i) : 0;
 		return ret;