UVa 11661 Burger Time? Solution

    #include <cstdio>
    int main(void){
        register char c;
        int d, i, ld, lr, temp, L;
        while(scanf("%d\n",&L) && L){
            d = 1<<25;
            lr = ld = -1;
            for(i = 0; i < L; i++){
                c = getc( stdin );
                if(c == '.') continue;
                if(c == 'R'){
                    if(ld != -1){
                        temp = i - ld;
                        if(temp < d) d = temp;
                    }
                    lr = i;
                } else if(c == 'D'){
                    if(lr != -1){
                        temp = i - lr;
                        if(temp < d) d = temp;
                    }
                    ld = i;
                } else if(c == 'Z'){
                    d = 0;
                    break;
                }
            }
            while(++i <= L) getc( stdin );
            printf("%d\n",d);
        }
        return 0;
    }