Submission #1345144

#TimeUsernameProblemLanguageResultExecution timeMemory
1345144chithanhnguyenHotspot (NOI17_hotspot)C++20
100 / 100
716 ms154732 KiB
/*
Author: Nguyen Chi Thanh - High School for the Gifted - VNU.HCM (i2528)
*/
#include <bits/stdc++.h>
using namespace std;

/* START OF TEMPALTE */

// #define int long long
#define ll long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) (1ll << (x))
#define SZ(a) ((int32_t)a.size())

#define debug(a, l, r) {for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';}

template<class X, class Y>
bool minimize(X &x, const Y &y) {
    if (x > y) {
        x = y;
        return true;
    } else return false;
}

template<class X, class Y>
bool maximize(X &x, const Y &y) {
    if (x < y) {
        x = y;
        return true;
    } else return false;
}

/* END OF TEMPALTE */

const int MAXN = 5005;
const int INF  = 1e9 + 5;
int n, m, dist[MAXN][MAXN], cnt[MAXN][MAXN];
ld res[MAXN];
vector<int> adj[MAXN];

void init() {
    cin >> n >> m;

    for (int i = 1; i <= m; ++i) {
        int u, v; cin >> u >> v;
        ++u; ++v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
}

void process_source(int u) {
    for (int i = 1; i <= n; ++i) dist[u][i] = INF;

    dist[u][u] = 0;
    cnt[u][u] = 1;
    queue<int> qu; qu.push(u);

    while (!qu.empty()) {
        int cur = qu.front();
        qu.pop();

        for (int v : adj[cur]) {
            if (dist[u][v] > dist[u][cur] + 1) {
                dist[u][v] = dist[u][cur] + 1;
                cnt[u][v] = cnt[u][cur];
                qu.push(v);
            } else if (dist[u][v] == dist[u][cur] + 1) {
                cnt[u][v] += cnt[u][cur];
            }
        }
    }
}

void solve() {
    for (int i = 1; i <= n; ++i)
        process_source(i);
    
    int k; cin >> k;
    while (k--) {
        int u, v; cin >> u >> v;
        ++u; ++v;

        for (int i = 1; i <= n; ++i) {
            if (dist[u][i] + dist[i][v] == dist[u][v]) {
                ll numpath = 1ll * cnt[u][i] * cnt[i][v];
                ll totalpath = cnt[u][v];
                ld ev = 1.0 * numpath / totalpath;
                res[i] += ev;
            }
        }
    }

    ld mx = res[1]; int opt = 1;
    for (int i = 2; i <= n; ++i) {
        if (res[i] > mx) {
            mx = res[i];
            opt = i;
        }
    }

    cout << opt - 1;
}

signed main() {
    #ifdef NCTHANH
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr); cout.tie(nullptr);

    init();
    solve();

    return 0;
}
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