hdu 2062搜索

挺简单，直接上代码。

/*

 * hdu2062/win.cpp

 * Created on: 2012-10-27

 * Author    : ben

 */

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <cmath>

#include <ctime>

#include <iostream>

#include <algorithm>

#include <queue>

#include <set>

#include <map>

#include <stack>

#include <string>

#include <vector>

#include <deque>

#include <list>

#include <functional>

#include <numeric>

#include <cctype>

using namespace std;

typedef long long LL;

const int MAXN = 22;

LL f[MAXN];

int ans[MAXN], N;

bool used[MAXN];

void init() {

    f[0] = 0;

    for(int i = 1; i <= 20; i++) {

        f[i] = i * (f[i - 1] + 1);

    }

}



int getnum(int t) {

    int i = 1;

    while(t > 1 || used[i]) {

        if(!used[i]) {

            t--;

        }

        i++;

    }

    return i;

}



void dfs(int step, LL M) {

    if(M <= 0) {

        ans[step] = -1;

        return ;

    }

    if(step == N) {

        return ;

    }

    int t = 1;

    while(M > f[N - step - 1] + 1) {

        t++;

        M -= f[N - step - 1] + 1;

    }

    ans[step] = getnum(t);

    used[ans[step]] = true;

    dfs(step + 1, M - 1);

}



int main() {

#ifndef ONLINE_JUDGE

    freopen("data.in", "r", stdin);

#endif

    init();

    LL M;

    while(scanf("%d%I64d", &N, &M) == 2) {

        fill(used, used + MAXN, false);

        dfs(0, M);

        printf("%d", ans[0]);

        for(int i = 1; i < N; i++) {

            if(ans[i] > 0) {

                printf(" %d", ans[i]);

            }else {

                break;

            }

        }

        putchar('\n');

    }

//    copy(f, f + 21, ostream_iterator<LL>(cout, "\t"));

    return 0;

}