题解 | #数制转换#

#include <stdio.h>
#include <string.h>

int main() {
    int a, b;
    char n[105];
    while (scanf("%d %s %d", &a, n, &b) != EOF) {
        int len = strlen(n);
        int ans = 0;
        for (int i = 0; i < len; i++) {
            ans *= a;
            if (n[i] >= '0' && n[i] <= '9') {
                ans += (n[i] - '0');
            } else if (n[i] >= 'a' && n[i] <= 'f') {
                ans += (n[i] - 'a') + 10;
            } else if (n[i] >= 'A' && n[i] <= 'F') {
                ans += (n[i] - 'A') + 10;
            }
        }
        char out[105];
        int cnt = 0;
        while (ans > 0) {
            int w = ans % b;
            if (w < 10) {
                out[cnt++] = w + '0';
            } else {
                out[cnt++] = (w - 10) + 'A';
            }
            ans /= b;
        }
        for (int i = cnt - 1; i >= 0; i--) {
            printf("%c", out[i]);
        }
        printf("\n");
    }
    return 0;
}