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// 179. Largest Number
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
* given a list of non-negative integers 'nums', arrange them such that they
* form the larget number and return it. since the result may be very large, so
* you need to return a string instead of an integer.
*/
int check_digit(int val) {
int digit = 0;
while (val) {
digit++;
val /= 10;
}
return digit;
}
char *int_to_str(int val) {
if (!val)
return "0";
int digit = check_digit(val);
char *res = malloc(digit + 1);
res[digit] = '\0';
int idx = digit - 1;
while (val) {
res[idx] = val % 10 + '0';
val /= 10;
idx--;
}
return res;
}
int cmp(const void *a, const void *b) {
char *aa = *(char **)a;
char *bb = *(char **)b;
int n = strlen(aa) + strlen(bb);
char *ab = malloc(n + 1), *ba = malloc(n + 1);
ab[n] = '\0';
ba[n] = '\0';
strcpy(ab, aa);
strcpy(&ab[strlen(aa)], bb);
strcpy(ba, bb);
strcpy(&ba[strlen(bb)], aa);
for (int i = 0; i < n; i++) {
if (ab[i] == ba[i])
continue;
return ba[i] - ab[i];
}
return 0;
}
char *largestNumber(int *nums, int nums_size) {
int n = nums_size, len = 0;
char **data = malloc(n * sizeof(char *));
bool zero = true;
for (int i = 0; i < n; i++) {
data[i] = int_to_str(nums[i]);
len += strlen(data[i]);
if (nums[i])
zero = false;
}
if (zero)
return "0";
qsort(data, n, sizeof(char *), cmp);
char *ans = malloc(len + 1);
int p = 0;
for (int i = 0; i < n; i++) {
strcpy(&ans[p], data[i]);
p += strlen(data[i]);
}
return ans;
}
int main() {
int n1[] = {10, 2}, n2[] = {3, 30, 34, 5, 9};
printf("%s\n", largestNumber(n1, 2)); // expect: 210
printf("%s\n", largestNumber(n2, 5)); // expect: 9534330
}
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