Submission #569226

#	Time	Username	Problem	Language	Result	Execution time	Memory
569226		Waratpp123	Love Polygon (BOI18_polygon)	C++14	29 / 100	284 ms	32196 KiB

polygon

#include<bits/stdc++.h>
using namespace std;
map<string,int> mp;
string ss[100010],se[100010];
vector<int> g[100010],gb[100010];
queue<int> topo,bfs;
int in[100010],dp[100010][2],sum,ch[100010],dp2[100010];
void dfs(int i,int p){
    for(auto x : gb[i]){
        if(x==p||in[x]>0) continue;
        dfs(x,i);
    }
    int mx=0;
    for(auto x : gb[i]){
        if(x==p||in[x]>0) continue;
        dp[i][1]+=dp[x][0];
        mx=max(mx,dp[x][1]-dp[x][0]);
    }
    dp[i][0]=mx+dp[i][1];
    dp[i][1]++;
}
int findloop(vector<int> t){
    if(t.size()==1) return 0;
    int mx=0,temp,n=t.size(),i,j;
    for(i=0;i<n;i++){
        dp2[i]=t[i];
        dp2[(i+1)%n]=max(dp2[i],t[(i+1)%n]);
        for(j=i+2;j<n+i;j++){
            dp2[j%n]=max(dp2[(j+n-1)%n],dp2[(j+n-2)%n]+t[j%n]);
        }
        for(j=i;j<n+i;j++) mx=max(mx,dp2[j%n]);
    }
    return mx;
}
int main(){
    int n,i,j;
    scanf("%d",&n);
    for(i=1;i<=n;i++){
        cin >> ss[i] >> se[i];
        mp[ss[i]]=i;
    }
    if(n%2!=0){
        printf("-1");
        return 0;
    }
    for(i=1;i<=n;i++){
        int sss=mp[ss[i]];
        int sse=mp[se[i]];
        g[sss].push_back(sse);
        gb[sse].push_back(sss);
        in[sse]++;
    }
    for(i=1;i<=n;i++){
        if(in[i]==0) topo.push(i);
    }
    while(!topo.empty()){
        i=topo.front();
        topo.pop();
        in[i]--;
        for(auto x : g[i]){
            in[x]--;
            if(in[x]==0){
                topo.push(x);
            }
        }
    }
    int cnt=0;
    int ans=0;
    for(i=1;i<=n;i++){
        if(in[i]>0){
            dfs(i,-1);
            ans+=dp[i][0];
        }
    }
    vector<int> t;
    for(i=1;i<=n;i++){
        if(in[i]>0){
            if(ch[i]==0){
                bfs.push(i);
                ch[i]=1;
                t.clear();
                while(!bfs.empty()){
                    j=bfs.front();
                    bfs.pop();
                    t.push_back(dp[j][1]-dp[j][0]);
                    for(auto x : g[j]){
                        if(ch[x]==0){
                            bfs.push(x);
                            ch[x]=1;
                        }
                    }
                }
                ans+=(findloop(t));
            }
        }
    }
    printf("%d\n",n-ans);
return 0;
}
/*
8
leonard emmy
ada emmy
isaac leonard
emmy pierre
pierre bernhard
bernhard emmy
sofia karl
karl sofia
*/

Compilation message (stderr)

polygon.cpp: In function 'int findloop(std::vector<int>)':
polygon.cpp:24:14: warning: unused variable 'temp' [-Wunused-variable]
   24 |     int mx=0,temp,n=t.size(),i,j;
      |              ^~~~
polygon.cpp: In function 'int main()':
polygon.cpp:67:9: warning: unused variable 'cnt' [-Wunused-variable]
   67 |     int cnt=0;
      |         ^~~
polygon.cpp:37:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~

• Subtask 1: 0 / 21
• Subtask 2: 0 / 25
• Subtask 3: 29 / 29
• Subtask 4: 0 / 25