From 4bd411139935c8147e20f82d4154ec25c85ab3bf Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Mon, 21 Sep 2026 00:45:05 +0800
Subject: leftBitCount

---
 bits.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/bits.c b/bits.c
index 8297011..c5c08fa 100644
--- a/bits.c
+++ b/bits.c
@@ -155,7 +155,29 @@ int logicalShift(int x, int n) {
  *   Difficulty: 4
  */
 int leftBitCount(int x) {
-    return 2;
+    int shift = 16;
+    int t = !((((x >> shift) & 0xFFFF) ^ 0xFFFF));
+    int count = t << 4;
+
+    shift = 24 + ~count + 1;
+    t = !((((x >> shift) & 0xFF) ^ 0xFF));
+    count = count + (t << 3);
+
+    shift = 28 + ~count + 1;
+    t = !((((x >> shift) & 0xF) ^ 0xF));
+    count = count + (t << 2);
+
+    shift = 30 + ~count + 1;
+    t = !((((x >> shift) & 0x3) ^ 0x3));
+    count = count + (t << 1);
+
+    shift = 31 + ~count + 1;
+    t = !((((x >> shift) & 0x1) ^ 0x1));
+    count = count + t;
+
+    count = count + !(~x);
+
+    return count;
 }
 
 /*
-- 
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