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一道很好的dfs加储存路径的题目  ：路径保存：每次dfs都存i 当大于max时 将临时数组保存到答案数组

并不是当 当前值大于最大值时更新路径

还要加上一个条件：能回去

#include<bits/stdc++.h>
using namespace  std;
int n;
int m1[][];
int valu[];
int ans[];int path[];
int maxi,len;

void dfs(int stepn,int sum,int cur)
{

   for(int i=cur+;i<=n;i++)
   {
       if(m1[cur][i])
       {
           path[stepn]=i;

           if(m1[i][n+])
           {

               path[stepn+]=;
               if(sum+valu[i]>maxi)
               {
                   maxi=sum+valu[i];
                   len=stepn+;
                   for(int j=;j<=len;j++)
                   {
                       ans[j]=path[j];
                   }

               }

           }

           dfs(stepn+,sum+valu[i],i);
       }

   }

}

int main()
{

  int cas;scanf("%d",&cas);int case1=;
  while(cas--)
  {
      maxi=;

      len=;
      ans[]=;
       memset(m1,,sizeof(m1));

      scanf("%d",&n);
      for(int i=;i<=n;i++)scanf("%d",&valu[i]);

      valu[]=valu[+n]=;

       int q;
        scanf("%d",&q);
      while(q--)
      {
          int a,b;
          scanf("%d%d",&a,&b);
          m1[a][b]=m1[b][a]=;

      }

      if(case1!=)
        printf("\n");
      printf("CASE %d#\n",case1++);

      dfs(,,);

      printf("points : %d\n",maxi);
      if(len!=)
      {
          printf("circuit : ");
          for(int i=;i<len;i++)
             printf("%d->",ans[i]);
          printf("%d\n",ans[len]);

      }

  }

return ;
}

还可以用dp来做

#include <stdio.h>
#include <string.h>
bool link[][];
int intrest[], dp[], last[], path[];
int main()
{
    int t, case_num = ;
    //freopen("input.txt", "r", stdin);
    scanf("%d", &t);
    while(t--)
    {
        int n, m, i, j;
        memset(link, , sizeof(link));
        memset(dp, , sizeof(dp));
        last[] = ; //last记录上一个走的城市的标号，last[1] = 0是为了让追溯到第一个城市之后就不继续追溯了
        scanf("%d", &n);
        if(case_num != )
            printf("\n");
        for(i = ; i <= n; i++)
        {
            scanf("%d", &intrest[i]);
        }
        intrest[i] = ; //注意i城市有趣度为0!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        scanf("%d", &m);
        for(int i = ; i < m; i++)
        {
            int a, b;
            scanf("%d%d", &a, &b);
            link[a][b] = link[b][a] = ;
        }
        for(i = ; i <= n+; i++) //假设目标城市标号为i(注意到达它之前经过的城市的标号都小于它)
        {
            for(j = ; j < i; j++)
                //遍历到达i城市之前所在的城市的标号的所有可能性，
                //更新到达i城的时候的有趣度之和为所有情况中最大的
            {
                if(dp[j]+intrest[i] > dp[i] && link[i][j])
                {
                    dp[i] = dp[j]+intrest[i];
                   last[i] = j;
                }
            }
        }
        j = ;
        i = n+;
        while(last[i])
        {
            path[j++] = last[i];
            i = last[i];
        }
        printf("CASE %d#\n", case_num++);
        printf("points : %d\n", dp[n+]);
        printf("circuit : ");
        for(i = j-; i >= ; i--)//注意输出的个数并非为城市数目！！！！！！！！！！！！！
        {
            printf("%d->", path[i]);
        }
        printf("1\n");
    }
    return ;
}

回顾

#include<iostream>
#include<queue>
#include<cstdio>
#include<cstring>
#include<vector>
#include<map>
#include<algorithm>
#include<cmath>
using namespace std;

#define N 105
#define inf 0x3f3f3f3f

int ans[N];
int path[N];
int n,maxx;
int mp[N][N];
int city[N];
int len;

void dfs(int cur,int interest,int num)
{
    for(int i=cur+;i<=n;i++)
    {
        if(mp[cur][i])
        {
            int t=interest+city[i];
            path[num]=i;
            if(t>maxx&&mp[i][n+])
            {    maxx=t;
                for(int i=;i<=num;i++)
                    ans[i]=path[i];
                    len=num;
            }
            dfs(i,t,num+);
        }
    }
}

int main()
{
    int cas;cin>>cas;
    for(int kase=;kase<=cas;kase++)
    {
        memset(mp,,sizeof mp);
        scanf("%d",&n);

        for(int i=;i<=n;i++)
            scanf("%d",&city[i]);
        city[n+]=city[]=;

        int m,a,b;
        cin>>m;
        while(m--)
        {
            scanf("%d%d",&a,&b);
            mp[a][b]=mp[b][a]=;
        }
        path[]=;
        maxx=;
        dfs(,,);

        if(kase!=)printf("\n");
        printf("CASE %d#\n",kase);
        printf("points : %d\ncircuit : ",maxx);
        for(int i=;i<=len;i++)
            printf("%d->",ans[i]);
        printf("%d\n",);
    }
}