1629.cpp

这是哈尔滨工业大学acmOJ的源代码

/*  This Code is Submitted by wywcgs for Problem 1629 on 2006-03-11 at 01:49:15 */ 
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <functional>
using namespace std;

char word[16], path[8] = "";
int len, r;
bool vst[16];

bool enumer(int);
inline int pow(int, int);

int main()
{
	while(scanf("%d %s", &r, word) != EOF && !(r == 0 && !strcmp(word, "END"))) {
		len = strlen(word); memset(vst, false, sizeof(vst));
		sort(word, word+len, greater<char>());
		printf("%s\n", enumer(0) ? path : "no solution");
	}
	
	return 0;
}

bool enumer(int n)
{
	int i;
	if(n == 5) {
		int d = 0;
		for(i = 0; i < 5; i++)
			d += pow(path[i]-'A'+1, i+1);
		return (d == r);
	} else {
		for(i = 0; i < len; i++) {
			if(vst[i]) continue;
			path[n] = word[i]; vst[i] = true;
			if(enumer(n+1)) return true;
			vst[i] = false;
		}
		return false;
	}
}
inline int pow(int b, int e)
{
	int i, k = -1;
	for(i = 0; i < e; i++) k *= -b;
	return k;
}