Number of one bits

Signed-off-by: Leo Ma <[email protected]>

Author: begeekmyfriend

190_reverse_bits/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test reverse_bits.c

190_reverse_bits/reverse_bits.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+static uint32_t reverseBits(uint32_t n)
+{
+    int i;
+    uint32_t res = 0;
+    for (i = 0; i < 32; i++) {
+        res <<= 1;
+        res |= n & 0x1;
+        n >>= 1;
+    }
+    return res;
+}
+
+int main(int argc, char **argv)
+{
+    if (argc != 2) {
+        fprintf(stderr, "Usage: ./test n\n");
+        exit(-1);
+    }
+
+    printf("%u\n", reverseBits(atoi(argv[1])));
+    return 0;
+}

191_number_of_one_bits/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test hamming_weight.c

191_number_of_one_bits/hamming_weight.c

@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+static int hammingWeight(uint32_t n)
+{
+    int count = 0;
+    while (n > 0) {
+        n = n & (n - 1);
+        count++;
+    }
+    return count;
+}
+
+int main(int argc, char **argv)
+{
+    if (argc != 2) {
+        fprintf(stderr, "Usage: ./test n\n");
+        exit(-1);
+    }
+
+    printf("%d\n", hammingWeight(atoi(argv[1])));
+    return 0;
+}