【题目链接】:http://codeforces.com/contest/801/problem/B
【题意】
定义一个对两个字符串x,y的f(x,y)函数;
返回的是一个字符串;
这个返回的字符串的每一位i是x和y在相应位置上的字符的较小值;
告诉你x和f(x,y);
求y;
【题解】
如果f(x,y)[i]==x[i]则y[i]=’z’;
否则
如果f(x,y)[i]>x[i]则y[i]=x[i]
否则
无解
【Number Of WA】
0
【完整代码】
#include <bits/stdc++.h>
using namespace std;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define LL long long
#define rep1(i,a,b) for (int i = a;i <= b;i++)
#define rep2(i,a,b) for (int i = a;i >= b;i--)
#define mp make_pair
#define ps push_back
#define fi first
#define se second
#define rei(x) cin >> x
#define pri(x) cout << x
#define ms(x,y) memset(x,y,sizeof x)
typedef pair<int,int> pii;
typedef pair<LL,LL> pll;
const int dx[9] = {0,1,-1,0,0,-1,-1,1,1};
const int dy[9] = {0,0,0,-1,1,-1,1,-1,1};
const double pi = acos(-1.0);
const int N = 110;
string x,y,z;
int main()
{
//freopen("F:\rush.txt","r",stdin);
cin >> x >> y;
int len = x.size();
z="";
rep1(i,0,len-1)
{
if (y[i]==x[i])
z+='z';
else
if (x[i]>y[i])
z+=y[i];
else
return cout << -1<<endl,0;
}
cout <<z<<endl;
//printf("
%.2lf sec
", (double)clock() / CLOCKS_PER_SEC);
return 0;
}