Submission #1087629

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087629		Whisper	Aesthetic (NOI20_aesthetic)	C++17	100 / 100	837 ms	71968 KiB

Aesthetic

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define REPD(i, a) for (int i = (a) - 1; i >= 0; --i)

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)


constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

/*
    Phu Trong from Nguyen Tat Thanh High School for gifted student
*/

template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }

template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }
#define MAX                 300005
int numNode, numEdge;
vector<int> G[MAX];
struct Edge{
    int u, v, w;
    Edge(){}
    Edge(int _u, int _v, int _w): u(_u), v(_v), w(_w){}

    int other(int x){return (x ^ u ^ v);}
} edge[MAX];
int minDist[2][MAX];

void dijkstra(int s, int minDist[]){
    for (int i = 1; i <= numNode; ++i) minDist[i] = LINF;
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> q;
    q.emplace(0, s);
    minDist[s] = 0;
    while(q.size()){
        int du, u; tie(du, u) = q.top(); q.pop();
        if(du > minDist[u]) continue;

        for(int&i : G[u]) {
            int v = edge[i].other(u);
            if(minimize(minDist[v], minDist[u] + edge[i].w)){
                q.emplace(minDist[v], v);
            }
        }
    }
}

int low[MAX], num[MAX], timeDfs = 0;

int suffix[MAX];
bool contain[MAX];
vector<pair<int, int>> newG[MAX];
bool ok = 0;

int value = 0;
void tarjan(int u, int p){
    if(u == numNode) contain[u] = true;
    low[u] = num[u] = ++timeDfs;
    for (pair<int, int>&x : newG[u]){
        int v = x.first, i = x.second;
        if(i ^ p){
            if(num[v]) minimize(low[u], num[v]);
            else{
                tarjan(v, i);
                minimize(low[u], low[v]);
                contain[u] |= contain[v];

                if(num[v] == low[v]){
                    if(!contain[v]) continue;
                    int eu = edge[i].u, ev = edge[i].v;
                    if(minDist[0][eu] + edge[i].w + minDist[1][ev] != minDist[0][numNode]) continue;
                    if(minDist[0][eu] + edge[i].w + minDist[1][ev] + suffix[i] >= minDist[0][numNode] + value)
                        ok = 1;
                }
            }
        }
    }
}

void process(void){
    cin >> numNode >> numEdge;
    int max_weight = 0;
    for (int i = 1; i <= numEdge; ++i){
        cin >> edge[i].u >> edge[i].v >> edge[i].w;
        G[edge[i].u].emplace_back(i);
        G[edge[i].v].emplace_back(i);
        maximize(max_weight, edge[i].w);
    }

    dijkstra(1, minDist[0]);
    dijkstra(numNode, minDist[1]);

    suffix[numEdge] = -LINF;
    for (int i = numEdge - 1; i >= 1; --i){
        maximize(suffix[i], suffix[i + 1]);
        maximize(suffix[i], edge[i + 1].w);
    }

    for (int i = 1; i <= numEdge; ++i){
        if(minDist[0][edge[i].u] > minDist[0][edge[i].v]) swap(edge[i].u, edge[i].v);
    }
    int l = 1, r = max_weight;
    int add = 0;

    auto check = [&](int val) -> bool{
        timeDfs = 0, ok = 0;
        value = val;
        for (int i = 1; i <= numNode; ++i) newG[i].clear(), contain[i] = num[i] = low[i] = 0;

        auto active = [&](int u, int v, int w, int x) -> bool{
            if(minDist[0][u] + minDist[1][v] + w < minDist[0][numNode] + x) return true;
            if(minDist[0][v] + minDist[1][u] + w < minDist[0][numNode] + x) return true;
            return false;
        };

        for (int u = 1; u <= numNode; ++u){
            for (int&i : G[u]){
                int v = edge[i].other(u);
                if(active(u, v, edge[i].w, val)) {
                    newG[u].emplace_back(v, i);
                }
            }
        }
        tarjan(1, 0);
        return (ok);
    };

    while(l <= r){
        int m = (l + r) >> 1;
        if(check(m)) l = m + 1, add = m;
        else r = m - 1;
    }

    cout << minDist[0][numNode] + add;
}
signed main(){
    #define name "Whisper"
    cin.tie(nullptr) -> sync_with_stdio(false);
    //freopen(name".inp", "r", stdin);
    //freopen(name".out", "w", stdout);
    process();
    return (0 ^ 0);
}

Compilation message (stderr)

Aesthetic.cpp: In lambda function:
Aesthetic.cpp:128:81: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  128 |         for (int i = 1; i <= numNode; ++i) newG[i].clear(), contain[i] = num[i] = low[i] = 0;
      |                                                                          ~~~~~~~^~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 7 / 7
• Subtask 4: 15 / 15
• Subtask 5: 16 / 16
• Subtask 6: 22 / 22
• Subtask 7: 27 / 27