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Submission #274225

# Submission time Handle Problem Language Result Execution time Memory
274225 2020-08-19T10:06:58 Z doowey Aesthetic (NOI20_aesthetic) C++14
13 / 100
 2000 ms 70452 KB 
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> pii;

#define fi first
#define se second
#define mp make_pair
#define fastIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

const int N = (int)3e5 + 10;
int u[N], v[N], w[N];
int p[N];

vector<pii> T[N];
ll dist[2][N];
bool has[N];
int n,m,c;

void dijik(int x){
    priority_queue<pii,vector<pii>,greater<pii>> gg;
    int node;
    for(int i = 1; i <= n; i ++ ){
        dist[c][i]=(ll)1e14;
        has[i]=false;
    }
    dist[c][x]=0ll;
    gg.push(mp(0,x));
    while(!gg.empty()){
        node = gg.top().se;
        gg.pop();
        if(has[node]) continue;
        has[node]=true;
        for(auto x : T[node]){
            if(dist[c][node] + w[x.se] < dist[c][x.fi]){
                dist[c][x.fi] = dist[c][node] + w[x.se];
                gg.push(mp(dist[c][x.fi], x.fi));
            }
        }
    }
    c++;
}

vector<pii> E[N];

int tin[N];
int low[N];

ll attm;
int tt;

bool bridge[N];

void dfs(int u, int par){
    tin[u] = ++tt;
    low[u] = tin[u];
    for(auto x : E[u]){
        if(x.fi == par) continue;
        if(tin[x.fi] != -1){
            low[u] = min(low[u], tin[x.fi]);
        }
        else{
            dfs(x.fi, u);
            low[u] = min(low[u], low[x.fi]);
            if(tin[u] < low[x.fi]){
                bridge[x.se] = true;
            }
        }
    }
}

int ids[N];
int id;

void dfs1(int u, int par){
    ids[u]=id;
    for(auto x : E[u]){
        if(ids[x.fi] != -1) continue;
        if(bridge[x.se]) continue;
        dfs1(x.fi, u);
    }
}

bool bad;

int pid[N];
int ip[N];

bool vis[N];

void dfs2(int u, int par){
    vis[u]=true;
    for(auto x : E[u]){
        if(vis[x.fi]) continue;
        if(bridge[x.se]){
            pid[ids[x.fi]] = ids[u];
            ip[ids[x.fi]] = x.se;
            dfs2(x.fi, u);
        }
        else{
            dfs2(x.fi, u);
        }
    }
}

bool check(ll dis){
    attm = dis;
    tt = 0;
    for(int i = 0 ; i < m ; i ++ ){
        bridge[i]=false;
    }
    for(int i = 1; i <= n; i ++ ){
        E[i].clear();
        vis[i]=false;
        tin[i] = -1, low[i] = -1;
        ids[i] = -1;
        pid[i] = -1;
        ip[i] = -1;
    }
    id = 0;
    for(int i = 0 ; i < m ; i ++ ){
        if(dist[0][u[i]] + w[i] + dist[1][v[i]] <= dis || dist[0][v[i]] + w[i] + dist[1][u[i]] <= dis){
            E[u[i]].push_back(mp(v[i], i));
            E[v[i]].push_back(mp(u[i], i));
        }
    }
    dfs(1, 0);
    if(tin[n] == -1) return false; // we assume it is reachable at this point
    bad = false;
    for(int i = 1; i <= n; i ++ ){
        if(tin[i] != -1 && ids[i] == -1){
            id ++ ;
            dfs1(i,-1);
        }
    }
    dfs2(1, 0);
    int node = ids[n];
    int ed;
    while(node != ids[1]){
        ed = ip[node];
        node = pid[node];
        if(dist[0][u[ed]] + dist[1][v[ed]] + w[ed] + p[ed+1] > dis && dist[1][u[ed]] + dist[0][v[ed]] + w[ed] + p[ed+1] > dis)
            return false;
    }
    return true;
}

int main(){
    fastIO;
    cin >> n >> m;
    for(int i = 0 ; i < m ; i ++ ){
        cin >> u[i] >> v[i] >> w[i];
        T[u[i]].push_back(mp(v[i],i));
        T[v[i]].push_back(mp(u[i],i));
    }
    dijik(1);
    dijik(n);
    ll li = 1, ri = (ll)1e15;
    for(int i = m-1; i >= 0 ; i -- ){
        p[i]=w[i];
        p[i]=max(p[i],p[i+1]);
    }
    ll mid;
    while(li < ri){
        mid = (li + ri) / 2;
        if(check(mid))
            ri = mid;
        else
            li = mid + 1;
    }
    cout << li << "\n";
    return 0;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 14464 KB Output is correct
2 Correct 10 ms 14464 KB Output is correct
3 Correct 11 ms 14464 KB Output is correct
4 Correct 11 ms 14464 KB Output is correct
5 Correct 15 ms 14464 KB Output is correct
6 Correct 11 ms 14500 KB Output is correct
7 Correct 15 ms 14464 KB Output is correct
8 Correct 11 ms 14592 KB Output is correct

Subtask #2
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 14464 KB Output is correct
2 Correct 10 ms 14464 KB Output is correct
3 Correct 11 ms 14464 KB Output is correct
4 Correct 11 ms 14464 KB Output is correct
5 Correct 15 ms 14464 KB Output is correct
6 Correct 11 ms 14500 KB Output is correct
7 Correct 15 ms 14464 KB Output is correct
8 Correct 11 ms 14592 KB Output is correct
9 Correct 15 ms 14848 KB Output is correct
10 Correct 16 ms 14848 KB Output is correct
11 Correct 17 ms 14848 KB Output is correct
12 Correct 18 ms 14848 KB Output is correct
13 Correct 15 ms 14848 KB Output is correct
14 Correct 14 ms 14848 KB Output is correct
15 Correct 14 ms 14848 KB Output is correct
16 Correct 18 ms 14848 KB Output is correct

Subtask #3
0 / 7.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2090 ms 68128 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2089 ms 69288 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #5
0 / 16.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2071 ms 70452 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #6
0 / 22.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2071 ms 70452 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #7
0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 14464 KB Output is correct
2 Correct 10 ms 14464 KB Output is correct
3 Correct 11 ms 14464 KB Output is correct
4 Correct 11 ms 14464 KB Output is correct
5 Correct 15 ms 14464 KB Output is correct
6 Correct 11 ms 14500 KB Output is correct
7 Correct 15 ms 14464 KB Output is correct
8 Correct 11 ms 14592 KB Output is correct
9 Correct 15 ms 14848 KB Output is correct
10 Correct 16 ms 14848 KB Output is correct
11 Correct 17 ms 14848 KB Output is correct
12 Correct 18 ms 14848 KB Output is correct
13 Correct 15 ms 14848 KB Output is correct
14 Correct 14 ms 14848 KB Output is correct
15 Correct 14 ms 14848 KB Output is correct
16 Correct 18 ms 14848 KB Output is correct
17 Execution timed out 2090 ms 68128 KB Time limit exceeded
18 Halted 0 ms 0 KB -