代码如下

#include <bits/stdc++.h>
using namespace std;
int s, t, w;
char c[27], z[27] = { 0, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
int a[27], jw, n, b[27], e[27];
int main()
{
	cin >> s >> t >> w;
	for (int i = 1; i <= w; i++)
		cin >> c[i];
	for (int i = 1; i <= w; i++)
	{
		a[i] = c[w + 1 - i] - 'a' + 1;
		e[i] = t - i + 1;
	}
	while (n < 5)
	{
		jw = 1;
		int flag0 = 1;
		for (int i = 1; i <= w; i++)
			if (a[i] != e[i])
				flag0 = 0;
		if (flag0)
			return 0;
		for (int i = 1; i <= w; i++)
		{
			a[i] = a[i] + jw;
			if (a[i] > t)
			{
				a[i] = s;
				jw = 1;
			}
			else
				jw = 0;
		}
		bool flag = 1;
		for (int i = 1; i <= w; i++)
			b[i] = a[i];
		sort (b + 1, b + w + 1);
		for (int i = 2; i <= w; i++)
			if (b[i] == b[i - 1])
				flag = 0;
		for (int i = 2; i <= w; i++)
			if (a[i] >= a[i - 1])
				flag = 0;
		if (flag)
		{
			for (int i = w; i >= 1; i--)
				cout << z[a[i]];
			n++;
			cout << endl;
		}
	}
}
	/*
	for (int i = 1; i <= w; i++)
		cout << a[i] << " ";
	*/