CF 8A Train and Peter

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前些日子看了一看 string 的用法没想到水到了这题

find函数如果找不到返回值为 -1 ？

题意正向反向顺序查找字串如果只有正向能找到输出 forward 如果反向能找到输出 backwards 如果双向都能找到输出both 找不到输出 fantasy

#include <iostream>#include <string>using namespace std;int main(){    string a,b,c;    string ret;    while(cin>>a>>b>>c)    {        ret = "";        for(int i = a.size()-1;i >= 0;i --) ret += a[i];        int fb = a.find(b,0),fc = a.find(c,fb+b.size());        int bb = ret.find(b,0),bc = ret.find(c,bb+b.size());//        cout<<fb<<" "<<fc<<" "<<bb<<" "<<bc<<endl;        if((fb == -1 || fc == -1) && (bb == -1 || bc == -1))        cout<<"fantasy"<<endl;        else if(fb != -1 && fc != -1 && bb != -1 && bc != -1)        cout<<"both"<<endl;        else if(fb != -1 && fc != -1 && (bb == -1 || bc == -1))        cout<<"forward"<<endl;        else        cout<<"backward"<<endl;    }    return 0;}

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