From 5d7cdc215e4ba1ec4cbb24c084cccb5e5e641468 Mon Sep 17 00:00:00 2001 From: Jack Sangdahl Date: Mon, 10 Mar 2025 00:33:44 -0600 Subject: 190. reverse bits --- reverse_bits.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 reverse_bits.c (limited to 'reverse_bits.c') diff --git a/reverse_bits.c b/reverse_bits.c new file mode 100644 index 0000000..d6bd60c --- /dev/null +++ b/reverse_bits.c @@ -0,0 +1,35 @@ +// 190. Reverse Bits +#include "leetcode.h" +#include + +/* + * reverse the bitof a given 32 bits unsigned integer. + */ + +uint32_t reverseBits(uint32_t n) { + n = ((n & 0xFFFF0000) >> 16) | ((n & 0x0000FFFF) << 16); + n = ((n & 0xFF00FF00) >> 8) | ((n & 0x00FF00FF) << 8); + n = ((n & 0xF0F0F0F0) >> 4) | ((n & 0x0F0F0F0F) << 4); + n = ((n & 0xCCCCCCCC) >> 2) | ((n & 0x33333333) << 2); + n = ((n & 0xAAAAAAAA) >> 1) | ((n & 0x55555555) << 1); + return n; +} + +int main() { + uint32_t n1 = 0b00000010100101000001111010011100; + uint32_t n2 = 0b11111111111111111111111111111101; + uint32_t r1 = reverseBits(n1); + uint32_t r2 = reverseBits(n2); + printf("%d (", r1); // expect: 964176192 (00111001011110000010100101000000) + while (r1) { + printf("%d", r1 & 1 ? 1 : 0); + r1 >>= 1; + } + printf(")\n"); + printf("%d (", r2); // expect: 3221225471 (10111111111111111111111111111111) + while (r2) { + printf("%d", r2 & 1 ? 1 : 0); + r2 >>= 1; + } + printf(")\n"); +} -- cgit v1.2.3