제출 #262215

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
262215		dantoh000	Islands (IOI08_islands)	C++14	80 / 100	1235 ms	131076 KiB

islands

#include <bits/stdc++.h>
#define fi first
#define se second
///Input format is not always nice, first nodes may not be in the keychain ring
using namespace std;
typedef long long ll;
typedef pair<int,int> ii;
int n;
vector<ii> G[1000005];
ll P[1000005];
int D[1000005];
int Pct;
bitset<1000005> vis[3];
ll ANS;
ll ans;
int cyclehead;
void dfs(int u, int p){
    vis[1][u] = 1;
    int join =0;
    int ct = 0;
    for (auto v: G[u]){
        if (vis[1][v.fi]){
            if (v.fi == p){
                if (ct == 1){
                    cyclehead = p;
                    //printf("%d %d repeated\n",u,v.fi);
                    vis[2][u]= 1;
                    join = v.se;
                }
                else {
                    ct++;
                }
                continue;
            }
            cyclehead = v.fi;
            vis[2][u] = 1;
            join = v.se;
            continue;
        }
        if (vis[0][v.fi] || vis[1][v.fi]) continue;
        dfs(v.fi,u);
        if (vis[2][v.fi] && v.fi != cyclehead) {
            vis[2][u] = 1;
            join = v.se;
            continue;
        }
    }
    if (vis[2][u]){
        //printf("at %d : %d\n",u,join);
        P[Pct] = u;
        D[Pct] = join;
        Pct++;
    }
    vis[0][u] = 1;
    vis[1][u] = 0;
}
ll dfs2(int u, int p){
    ll d2 = 0;
    ll d = 0;
    for (auto v: G[u]){
        if (v.fi == p || vis[2][v.fi]) continue;
        ll nd = dfs2(v.fi,u)+v.se;
        if (d <= nd){
            d2 = d;
            d = nd;
        }
        else d2 = max(d2,nd);
    }
    ans = max(ans,d2+d);
    return d;
}
ll solve(int root){
    ans = Pct = 0;
    dfs(root,-1);
    //printf("at %d\n",root);
    reverse(P,P+Pct);
    reverse(D,D+Pct);
    for (int i = 0; i < Pct; i++){
        P[i] = dfs2(P[i],-1);
        //printf("%d %d\n",P[i],D[i]);
    }
    if (Pct == 2){
        return max(ans,P[0]+P[1]+max(D[0],D[1]));
    }
    ll S = 0;
    ll Sl = 0;
    for (int i = 0; i < Pct; i++){
        S += D[i];
    }
    ll MX = P[0];
    ll MX2 = P[0];
    for (int i = 1; i < Pct; i++){
        ll x = P[i];
        //printf("at %lld %lld\n",d[x],Sl[x]);
        //printf("MX: %lld + %lld\n",MX,d[x] + Sl[x]);
        //printf("MX2: %lld + %lld\n",MX2,S + d[x] - Sl[x]);
        Sl += D[i-1];
        ans = max(ans, x + Sl + MX);
        ans = max(ans, S + x - Sl + MX2);
        MX = max(MX, x - Sl);
        MX2 = max(MX2, x + Sl);
    }
    //printf("%lld max\n",ans);
    return ans;
}
int main(){
    scanf("%d",&n);
    for (int i = 1; i <= n; i++){
        int j,L;
        scanf("%d%d",&j,&L);
        G[i].push_back({j,L});
        G[j].push_back({i,L});
    }
    for (int i = 1; i <= n; i++){
        if (vis[0][i] == 0){
            ANS += solve(i);
        }
    }
    printf("%lld",ANS);
}

컴파일 시 표준 에러 (stderr) 메시지

islands.cpp: In function 'int main()':
islands.cpp:107:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  107 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
islands.cpp:110:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  110 |         scanf("%d%d",&j,&L);
      |         ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 33 / 33
• Subtask 2: 3 / 3
• Subtask 3: 4 / 4
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10