Submission #1104793

#	Time	Username	Problem	Language	Result	Execution time	Memory
1104793		SoMotThanhXuan	Valley (BOI19_valley)	C++17	100 / 100	99 ms	37924 KiB

valley

// absolutely incredible
#include <bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = a; i <= b; ++i)
#define REP(i, a, b) for(int i = a; i >= b; --i)
#define left _________left
#define right _________right
#define NAME ""
const int mod = 1e9 + 7;
bool maximize(int &u, int v){
    if(v > u){
        u = v;
        return true;
    }
    return false;
}
bool minimize(int &u, int v){
    if(v < u){
        u = v;
        return true;
    }
    return false;
}
bool maximizell(long long &u, long long v){
    if(v > u){
        u = v;
        return true;
    }
    return false;
}
bool minimizell(long long &u, long long v){
    if(v < u){
        u = v;
        return true;
    }
    return false;
}
int fastPow(int a, int n){
    if(n == 0) return 1;
    int t = fastPow(a, n >> 1);
    t = 1ll * t * t % mod;
    if(n & 1) t = 1ll * t * a % mod;
    return t;
}
void add(int &u, int v){
    u += v;
    if(u >= mod) u -= mod;
}
void sub(int &u, int v){
    u -= v;
    if(u < 0) u += mod;
}
const int maxN = 1e5 + 5;
int n, q, s, e, cnt, in[maxN], out[maxN], par[17][maxN];
vector<pair<int, int>> adj[maxN];
pair<int, int> edge[maxN];
const long long INFLL = 1e18;
long long Min[17][maxN], f[maxN], d[maxN];
void dfs(int u = e){
    in[u] = ++cnt;
    for(auto [v, w] : adj[u]){
        if(in[v])continue;
        d[v] = d[u] + w;
        par[0][v] = u;
        dfs(v);
        minimizell(f[u], f[v] + w);
    }
    long long rem = f[u] != INFLL ? f[u] - d[u] : INFLL;
    for(auto [v, w] : adj[u]){
        if(in[v] > in[u]){
            Min[0][v] = rem;
        }
    }
    out[u] = cnt;
}
bool inside(int u, int v){
    return in[u] <= in[v] && out[u] >= out[v];
}
long long get(int c, int v){
    long long res = f[c] != INFLL ? f[c] - d[c] : INFLL;
    REP(i, 16, 0){
        if(inside(v, par[i][c])){
            minimizell(res, Min[i][c]);
            c = par[i][c];
        }
    }
    return res;
}
void solve(){
    cin >> n >> s >> q >> e;
    FOR(i, 1, n - 1){
        int u, v, w;
        cin >> u >> v >> w;
        edge[i] = make_pair(u, v);
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }
    FOR(i, 1, n)f[i] = INFLL;
    FOR(i, 1, s){
        int u;
        cin >> u;
        f[u] = 0;
    }
    dfs();
    FOR(j, 1, 16){
        FOR(i, 1, n){
            par[j][i] = par[j - 1][par[j - 1][i]];
            Min[j][i] = min(Min[j - 1][i], Min[j - 1][par[j - 1][i]]);
        }
    }
    while(q--){
        int id, c;
        cin >> id >> c;
        auto [u, v] = edge[id];
        if(in[u] > in[v])swap(u, v);
        if(!inside(v, c)){
            cout << "escaped\n";
            continue;
        }
        long long rem = get(c, v);
        if(rem == INFLL){
            cout << "oo\n";
        }else cout << rem + d[c] << "\n";
    }
}
int main(){
    if(fopen(NAME".inp", "r")){
        freopen(NAME".inp", "r", stdin);
        freopen(NAME".out", "w", stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int t = 1;
//    cin >> t;
    while(t--){
        solve();
    }
    return 0;
}

Compilation message (stderr)

valley.cpp: In function 'int main()':
valley.cpp:128:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  128 |         freopen(NAME".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:129:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  129 |         freopen(NAME".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 23 / 23
• Subtask 4: 41 / 41