Submission #1123917

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123917		vjudge	Aesthetic (NOI20_aesthetic)	C++20	100 / 100	689 ms	85000 KiB

Aesthetic

#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define F first
#define S second
#define ALL(x) x.begin(),x.end()
#define random(l, r) (l + rand() % (r - l + 1))
#define int long long
#define maxn 300005
#define bit(x, i) ((x >> i) & 1)
#define pii pair<int, int>
#define MOD 1000000000000000007
#define Task "A"
using namespace std;
vector<pair<int, pii> > v[maxn];
vector<int> T[maxn],W[maxn];
int d1[maxn],dn[maxn], f[maxn], g[maxn],ea[maxn],eb[maxn],ec[maxn], par[maxn],path[maxn],wh[maxn];
multiset<pair<int,int> > S;
int n,m;
void ad(int x)
{
    g[x] = 1;
    for(auto E : v[x])
    {
        int y = E.F, l = E.S.F,  u= E.S.S;
        auto it= S.find({dn[y] + l + d1[x], u});
        if(g[y] == 1) S.erase(it);
        if(g[y] == 0) S.insert({dn[x] + l + d1[y], u});
    }
}
void dfs(int x, int p)
{
    if(path[x]) wh[x] = x;
    else wh[x] = wh[p];
    T[wh[x]].push_back(x);
    for(int y : W[x])
    {
        dfs(y, x);
    }
}
int A = 0;
signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if(fopen(Task".inp", "r"))
    {
        freopen(Task".inp", "r", stdin);
        freopen(Task".out", "w", stdout);
    }
    cin >> n >> m;
    for(int i = 0; i < m; i++)cin >> ea[i]>>eb[i]>>ec[i];
    for(int i = m-1; i >= 0; i--)
    {
        int a = ea[i], b = eb[i], c = ec[i];
        if(a != b)
        {
            v[a].push_back({b, {c,A}});
            v[b].push_back({a, {c,A}});
        }
        A = max(A, c);
    }
    for(int i = 1; i <= n; i++)d1[i] = dn[i] = MOD;
    d1[1] = 0;
    dn[n] = 0;
    priority_queue<pii > q;
    q.push({0, 1});
    while(q.size())
    {
        int x = q.top().S;
        q.pop();
        if(f[x]) continue;
        f[x] = 1;
        for(auto E: v[x])
        {
            int y = E.F, l = E.S.F;
            if(!f[y] && d1[y] > d1[x] + l)
            {
                d1[y] = d1[x] + l;
                par[y] = x;
                q.push({-d1[y], y});
            }
        }
    }
    q.push({0, n});
    for(int i = 1; i <= n; i++)f[i] = 0;
    while(q.size())
    {
        int x = q.top().S;
        q.pop();
        if(f[x]) continue;
        f[x] = 1;
        for(auto E: v[x])
        {
            int y = E.F, l = E.S.F;
            if(!f[y] && dn[y] > dn[x] + l)
            {
                dn[y] = dn[x] + l;
                q.push({-dn[y], y});
            }
        }
    }
    int ans = d1[n];
    int X = n;
    while(1)
    {
        path[X] = 1;
        if(X == 1) break;
        X = par[X];
    }
    for(int i = 1; i <= n; i++)W[par[i]].push_back(i);
    dfs(1,0);
    int x = n;
    while(1)
    {
        for(int y : T[x])ad(y);
        if(x == 1) break;
        x = par[x];
        if(S.size() == 0) continue;
        int U = S.begin()->F + S.begin()->S;
        auto it = S.begin();
        it++;
        if(it != S.end()) U = min(U, it->F);
        ans = max(ans, U);
    }
    cout<<ans<<endl;
}

Compilation message (stderr)

Aesthetic.cpp: In function 'int main()':
Aesthetic.cpp:49:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |         freopen(Task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Aesthetic.cpp:50:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |         freopen(Task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• 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