Submission #217473

#	Time	Username	Problem	Language	Result	Execution time	Memory
217473		tatyam	Islands (IOI08_islands)	C++17	21 / 100	532 ms	131076 KiB

islands

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define name3(a,b,c,d,...) d
#define rep1(a) for(int i = 0; i < a; i++)
#define rep3(i,a,b) for(int i = a; i < b; i++)
#define rep(...) name3(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep(a) for(ll i = a; i--; )
#define each(i,a) for(auto&& i : a)
#define all(a) begin(a), end(a)
template<class T, class U> bool chmin(T& a, const U& b){ if(a > b){ a = b; return 1; } return 0; }
template<class T, class U> bool chmax(T& a, const U& b){ if(a < b){ a = b; return 1; } return 0; }


vector<bool> used;
vector<vector<pii>> g;
ll ans = 0;
void solve(int start){
    if(used[start]) return;
    vector<int> list = {start};
    used[start] = 1;
    rep(list.size()){
        int at = list[i];
        each(i, g[at]) if(!used[i.first]){
            used[i.first] = 1;
            list.push_back(i.first);
        }
    }
    ll mx = 0;
    int dex = -1;
    unordered_map<int, ll> dp;
    each(i, list) if(g[i].size() == 1){
        ll cnt = 0;
        int at = i;
        while(g[at].size() < 3){
            cnt += g[at][0].second;
            at = g[at][0].first;
        }
        chmax(dp[at], cnt);
        if(chmax(mx, cnt)) dex = at;
    }
    if(!mx){
        int min = 0x3fffffff;
        each(at, list){
            ans += g[at][0].second;
            chmin(min, g[at][0].second);
        }
        ans -= min;
        return;
    }
    vector<int> circle, dist;
    int at = dex;
    do{
        circle.push_back(at);
        dist.push_back(g[at][0].second);
        at = g[at][0].first;
    } while(at != dex);
    circle.push_back(at);
    dp[dex] = 0;
    auto dp2 = dp;
    rep(i, 1, dist.size()) chmax(dp[circle[i + 1]], dp[circle[i]] + dist[i]);
    rrep(dist.size() - 1) chmax(dp2[circle[i]], dp2[circle[i + 1]] + dist[i]);
    ans += mx + max(dp[dex], dp2[dex]);
}
int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    used.resize(n);
    g.resize(n);
    rep(n){
        int a, b;
        cin >> a >> b;
        a--;
        g[i].emplace_back(a, b);
    }
    rep(n) g[g[i][0].first].emplace_back(i, g[i][0].second);
    rep(n) solve(i);
    cout << ans << endl;
}

Compilation message (stderr)

islands.cpp: In function 'void solve(int)':
islands.cpp:6:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define rep1(a) for(int i = 0; i < a; i++)
                                  ^
islands.cpp:5:28: note: in expansion of macro 'rep1'
 #define name3(a,b,c,d,...) d
                            ^
islands.cpp:8:18: note: in expansion of macro 'name3'
 #define rep(...) name3(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)
                  ^~~~~
islands.cpp:23:5: note: in expansion of macro 'rep'
     rep(list.size()){
     ^~~
islands.cpp:7:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define rep3(i,a,b) for(int i = a; i < b; i++)
                                      ^
islands.cpp:5:28: note: in expansion of macro 'rep3'
 #define name3(a,b,c,d,...) d
                            ^
islands.cpp:8:18: note: in expansion of macro 'name3'
 #define rep(...) name3(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)
                  ^~~~~
islands.cpp:62:5: note: in expansion of macro 'rep'
     rep(i, 1, dist.size()) chmax(dp[circle[i + 1]], dp[circle[i]] + dist[i]);
     ^~~

• Subtask 1: 21 / 33
• Subtask 2: 0 / 3
• Subtask 3: 0 / 4
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10