【题解】洛谷 P1061 Jam的计数法

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
int small_num;
int big_num;
int number;
int num;
int Jam[30];
inline int is_right()
{
	bool v[30];
	memset(v,true,sizeof(v));
	for(int i=1;i<=number;i++)
	{
		if(!v[Jam[i]]) return false;
		else v[Jam[i]]=false;
		if(Jam[i]<Jam[i-1]) return false;
	}
	return true;
}
int main()
{
	scanf("%d %d %d",&small_num,&big_num,&number);
	for(int i=1;i<=number;i++)
	{
		char c;
		cin>>c;
		Jam[i]=c-'a'+1;
	}
	while(Jam[1]<big_num)
	{
		Jam[number]+=1;
		for(int i=number;i>=1;i--)
		{
			if(Jam[i]>big_num)
			{
				Jam[i-1]+=1;
				Jam[i]=Jam[i-1]-1;
			}
		}
		if(is_right())
		{
			for(int i=1;i<=number;i++)
				cout<<(char)(Jam[i]-1+'a');
			num++;
			cout<<endl;
		}
		if(num==5) return 0;
	}
	return 0; 
}