Submission #516338

#	Time	Username	Problem	Language	Result	Execution time	Memory
516338		kingline	Valley (BOI19_valley)	C++17	100 / 100	232 ms	54488 KiB

valley

/*#pragma GCC optimize("O3")
#pragma GCC target ("avx2")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")*/
#include <bits/stdc++.h>
#define file(data) freopen(data".in", "r", stdin); freopen(data".out", "w", stdout);
#define pb push_back
//#define ios ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define all(data) data.begin() , data.end()
#define endl '\n'
//freopen("nenokku_easy.in", "r", stdin);
//freopen("nenokku_easy.out", "w", stdout);
#define int long long
#define pii pair < int, int >
#define pll pair < long long, long long >

using namespace std;

typedef long long ll;
const int N = 1e5 + 5;
const int M = 305;
const int mod = 1e9 + 7;
const ll INF = 1e18;
const int lg = 20;
const long double limit = 1.0;

int n, s, q, e, tin[N], tout[N], a[N], b[N], w[N], h[N], d[N], dist[N], up[N][lg], mn[N][lg];
bool shop[N];

vector < pair < int, int > > g[N];

int sz;
void dfs(int v, int pr) {
    if(shop[v]) d[v] = 0;
    else d[v] = INF;
    tin[v] = ++sz;
    h[v] = h[pr] + 1;
    for(int i = 0; i < g[v].size(); i++) {
        int to = g[v][i].first, len = g[v][i].second;
        if(to != pr) {
            dist[to] = dist[v] + len;
            dfs(to, v);
            d[v] = min(d[v], d[to] + len);
        }
    }
    tout[v] = sz;
}

void dfs2(int v, int pr) {
    up[v][0] = pr;
    mn[v][0] = min(-dist[v] + d[v], -dist[pr] + d[pr]);
    for(int i = 1; i < lg; i++) {
        mn[v][i] = min(mn[v][i - 1], mn[up[v][i - 1]][i - 1]);
        up[v][i] = up[up[v][i - 1]][i - 1];
    }
    for(int i = 0; i < g[v].size(); i++) {
        int to = g[v][i].first, len = g[v][i].second;
        if(to != pr) {
            dfs2(to, v);
        }
    }
}

bool upper(int x, int y) {
    return tin[x] <= tin[y] && tout[x] >= tout[y];
}

int get(int anc, int x) {
    int res = -dist[x] + d[x];
    for(int i = lg - 1; i >= 0; i--) {
        if(!upper(up[x][i], anc)) {
            res = min(res, mn[x][i]);
            x = up[x][i];
        }
    }
    if(x != anc) {
        res = min(res, mn[x][0]);
    }
    return res;
}

main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    //file("threesum");
    cin >> n >> s >> q >> e;
    for(int i = 1; i < n; i++) {
        cin >> a[i] >> b[i] >> w[i];
        g[a[i]].pb({b[i], w[i]});
        g[b[i]].pb({a[i], w[i]});
    }
    for(int i = 1; i <= s; i++) {
        int z; cin >> z;
        shop[z] = 1;
    }
    dfs(e, e);
    dfs2(e, e);
    while(q--) {
        int block, now;
        cin >> block >> now;
        if(h[a[block]] > h[b[block]]) swap(a[block], b[block]);
        if(!upper(b[block], now)) {
            cout << "escaped\n";
        } else if(d[b[block]] == INF) {
            cout << "oo\n";
        } else {
            if(shop[now]) cout << "0\n";
            else {
                cout << dist[now] + get(b[block], now) << endl;
            }
        }
    }
}

Compilation message (stderr)

valley.cpp: In function 'void dfs(long long int, long long int)':
valley.cpp:39:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |     for(int i = 0; i < g[v].size(); i++) {
      |                    ~~^~~~~~~~~~~~~
valley.cpp: In function 'void dfs2(long long int, long long int)':
valley.cpp:57:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   57 |     for(int i = 0; i < g[v].size(); i++) {
      |                    ~~^~~~~~~~~~~~~
valley.cpp:58:33: warning: unused variable 'len' [-Wunused-variable]
   58 |         int to = g[v][i].first, len = g[v][i].second;
      |                                 ^~~
valley.cpp: At global scope:
valley.cpp:83:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   83 | main() {
      | ^~~~

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