1059 SMS

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

int start,m;
int key();
char kb[11][5]= {"","ABC","DEF","GHI","JKL","MNO","PQRS","TUV","WXYZ"};
char out[85]= {'\0'};
int main()
{
    int n,i,h,v;

    scanf("%d%d%d",&n,&start,&m);
    start-=1;
    key();
    for(i=0; i<n-1; i++)
    {
        scanf("%d%d%d",&h,&v,&m);
        start=start+h+(v*3);
        key();
        //printf("---%s---\n",out);
    }
    if(strlen(out)==0)
    {
        printf("null");
        return 0;
    }
    printf("%s",out);
    return 0;
}

int key()
{
    int len=strlen(out),i;
    if(start==0 && len>0)
    {
        for(i=len-1;i>=len-m;i--)
        {
            out[i]='\0';
            if(i<=0) break;
        }
        return 0;
    }
    if(start==6 || start==8)
    {
        m%=4;
        if(m==0) m=4;
        m--;
        out[len]=kb[start][m];
    }
    else
    {
        m%=3;
        if(m==0) m=3;
        m--;
        out[len]=kb[start][m];
    }

    return 0;
}