sgu 160 分类： sgu 2015-04-22 19:51 43人阅读 评论(0) 收藏

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DP
记录每个数是否能生成[ f(i) ]，
及它是由如何是生成的。。。[ fr(i) ]

转移方程见代码，没加优化似乎 31ms 。。。

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#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define Mp(x,y) std::make_pair(x,y)
#define num first
#define si second
const int MAXN = 1e4+3, MAXM = 1e3+3;
typedef std::pair<int,int> FrNode;


int n, m, a[MAXN] = {0};
int f[MAXM] = {0};
FrNode fr[MAXM];

void DFS(int a)
{
    if(fr[a].num) DFS(fr[a].num);

    printf("%d ",fr[a].si);
}

int main()
{
    bool flag = false;

#ifndef ONLINE_JUDGE
    freopen("sgu160.in","r",stdin);
    freopen("sgu160.out","w",stdout);
#endif

    scanf("%d%d",&n,&m);
    for(int i = 1; i <= n; i++)
       scanf("%d",a+i);

    for(int i = 1; i <= n; i++)
    {
      for(int j = 1,k; j < m; j++)
        if(f[j] && !f[k = j*a[i]%m] && fr[j].si != i)  
           f[k] = 1, fr[k] = Mp(j,i);   

      if(!f[a[i]]) f[a[i]] = 1, fr[a[i]] = Mp(0,i);
    }

    for(int i = m-1; i > 0; i--)
      if(f[i]) {printf("%d\n",i),DFS(i); flag = true; break;}

    if(!flag) puts("1");

#ifndef ONLINE_JUDGE
    fclose(stdin);
    fclose(stdout);
#endif
    return 0;           
}

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