1B - Spreadsheet (WA test 6, don't know why)

#include <iostream>
#include <cmath>
#include <cctype>
#include <cstdio>
#include <cstring>
using namespace std;

int N;
char buf[1000];

void Converti(int c) {
    int x=0, prec=0;
    while(prec + pow(26, x) <= c) {
        prec += pow(26, x);
        x++;
    }
    x--;
    for(; x>=0; x--) {
        prec -= pow(26, x);
        int t = (int)( (double)c / pow(26, x) );
        while(x > 0 && (c-(pow(26, x)*t)) < prec) t--;
        printf("%c", ('A' + (t-1)%26));
    }
}

int main() {
    scanf("%d", &N);
    for(int i=0; i < N; i++) {
        scanf("%s", buf);
        int r=0, c=0;
        if( sscanf(buf, "R%dC%d", &r, &c) == 2) { Converti(c); printf("%d\n", r); }
        else {
            r=0;
            c=0;
            for(int i=0; i < (int)strlen(buf); i++) {
                if(isdigit(buf[i])) r = r*10 + (buf[i] - '0');
                else c = c*26 + (buf[i] - 'A' + 1);
            }
            printf("R%dC%d\n", r, c);
        }
    }
    return 0;
}