leetcode

commit 378fbb0034a1d49b261f540a4b3cf0049e8b6803
parent 1936828618e8dfff65ac1f88e806873f92d848fd
Author: Jack Sangdahl <jack@pngu.org>
Date:   Tue, 10 Mar 2026 20:28:54 -0600

1009. complement of base 10 integer

Diffstat:
M
complement_base_10_int.c
 | 
22
+++++++++++++++-------
M
complement_base_10_int.py
 | 
5
+----

2 files changed, 16 insertions(+), 11 deletions(-)
diff --git a/complement_base_10_int.c b/complement_base_10_int.c
@@ -8,14 +8,22 @@
  */
 
 int bitwiseComplement(int n) {
-  int c = 1;
-  while (c < n)
-    c = (c << 1) + 1;
-  return n ^ c;
+  if (!n)
+    return 1;
+  unsigned int mask = ~0;
+  while (mask & n)
+    mask <<= 1;
+  return ~n ^ mask;
 }
 
 int main() {
-  printf("%d\n", bitwiseComplement(5));  // expect: 2
-  printf("%d\n", bitwiseComplement(7));  // expect: 0
-  printf("%d\n", bitwiseComplement(10)); // expect: 5
+  int r1 = bitwiseComplement(5);
+  int r2 = bitwiseComplement(7);
+  int r3 = bitwiseComplement(10);
+  printf("%d\n", r1); // expect: 2
+  assert(r1 == 2);
+  printf("%d\n", r2); // expect: 0
+  assert(r2 == 0);
+  printf("%d\n", r3); // expect: 5
+  assert(r3 == 5);
 }
diff --git a/complement_base_10_int.py b/complement_base_10_int.py
@@ -13,10 +13,7 @@ class Solution(object):
         :type n: int
         :rtype: int
         """
-        c = 1
-        while n > c:
-            c = c * 2 + 1
-        return c - n
+        return (1 << len(bin(n)) >> 2) - n - 1
 
 
 if __name__ == "__main__":