Next highest int from digits: Difference between revisions
Added C solution
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Line 56:
;Optional stretch goal:
* 9589776899767587796600
=={{header|C}}==
<lang c>#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
void swap(char* str, int i, int j) {
char c = str[i];
str[i] = str[j];
str[j] = c;
}
void reverse(char* str, int i, int j) {
for (; i < j; ++i, --j)
swap(str, i, j);
}
bool next_permutation(char* str) {
int len = strlen(str);
if (len < 2)
return false;
for (int i = len - 1; i > 0; ) {
int j = i, k;
if (str[--i] < str[j]) {
k = len;
while (str[i] >= str[--k]) {}
swap(str, i, k);
reverse(str, j, len - 1);
return true;
}
}
return false;
}
uint32_t next_highest_int(uint32_t n) {
char str[16];
snprintf(str, sizeof(str), "%u", n);
if (!next_permutation(str))
return 0;
return strtoul(str, 0, 10);
}
int main() {
uint32_t numbers[] = {0, 9, 12, 21, 12453, 738440, 45072010, 95322020};
const int count = sizeof(numbers)/sizeof(int);
for (int i = 0; i < count; ++i)
printf("%d -> %d\n", numbers[i], next_highest_int(numbers[i]));
// Last one is too large to convert to an integer
const char big[] = "9589776899767587796600";
char next[sizeof(big)];
memcpy(next, big, sizeof(big));
next_permutation(next);
printf("%s -> %s\n", big, next);
return 0;
}</lang>
{{out}}
<pre>
0 -> 0
9 -> 0
12 -> 21
21 -> 0
12453 -> 12534
738440 -> 740348
45072010 -> 45072100
95322020 -> 95322200
9589776899767587796600 -> 9589776899767587900667
</pre>
=={{header|C++}}==
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