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# include <stdlib.h>
# include <stdio.h>
# include <string.h>
# include <limits.h>
/*
* See ../README.md
*/
/*
* Run as: cc -o ch-2.o ch-2.c; ./ch-2.o < input-file
*/
int main (void) {
unsigned long long d;
while (scanf ("%llu", &d) == 1) {
char b [LONG_BIT + 1];
/*
* Transfer the decimal number into a binary representation,
* LSB first.
*/
for (size_t i = 0; i < LONG_BIT; i ++) {
b [i] = (d & 1);
d = d >> 1;
}
/*
* End with a 0
*/
b [LONG_BIT] = 0;
/*
* Count the number of 0s at the beginning, followed by a count of
* the number of 1s.
*/
size_t count_0 = 0;
size_t count_1 = 1;
while (!b [count_0]) {
count_0 ++;
}
while (b [count_0 + count_1]) {
count_1 ++;
}
/*
* Now, b [count_0 + count_1 - 1] == 1 and
* b [count_0 + count_1] == 0.
* Swap those two, and place the 1s and 0s
*/
b [count_0 + count_1] = 1;
b [count_0 + count_1 - 1] = 0;
count_1 --;
for (size_t i = 0; i < count_1; i ++) {
b [i] = 1;
}
for (size_t i = count_1; i < count_1 + count_0; i ++) {
b [i] = 0;
}
/*
* Turn binary expansion back to decimal
*/
d = 0;
unsigned long long p2 = 1;
for (size_t i = 0; i < LONG_BIT; i ++) {
d += p2 * b [i];
p2 *= 2;
}
printf ("%llu\n", d);
}
}
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