poj 1750 Dictionary

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>using namespace std;#define maxl 20char st[2][maxl];int main(){    int sum = 0;    int i = 0;    st[1][0] = '';    while (scanf("%s", st[i]) != EOF)    {        int same = 0;        for (int j = 0; j < sum + 1; j++) if (st[i][j] == st[i ^ 1][j] && st[i][j] != 0)     same++; else     break;        if (same == sum + 1) sum++;        else sum = same;        for (int j = 0; j < sum; j++) putchar(' ');        printf("%sn", st[i]);        i ^= 1;    }    return 0;}