1146 ID Codes

题目链接: http://poj.org/problem?id=1146

题意: 给定一个字符串(长度不超过50), 求这个字符串的下一个字典序的字符串, 如果已经是最大字典序, 那么输出 "No successor".

分析: <algorithm>中有一个现成的next_permutation(begin, end), 对输入的字符串进行排列.

原型如下:

template<class BidirectionalIterator>  
bool next_permutation(  
      BidirectionalIterator _First,   
      BidirectionalIterator _Last  
);  
template<class BidirectionalIterator, class BinaryPredicate>  
bool next_permutation(  
      BidirectionalIterator _First,   
      BidirectionalIterator _Last,  
      BinaryPredicate _Comp  
 );

AC代码:

#include <iostream>
#include <algorithm>
#include <string>
using namespace std;
string line;

bool comp(char a, char b){
    return a>b;
}

int main(){
    while(cin>>line){
        if(line.at(0) == '#')
            break;
        string s(line);
        sort(s.begin(),s.end(),comp);
        if(line == s){
            cout<<"No Successor"<<endl;
            continue;
        }
        next_permutation(line.begin(),line.end());
        cout<<line<<endl;
    }
    return 0;
}