Submission #91056

#	Time	Username	Problem	Language	Result	Execution time	Memory
91056		inom	Shymbulak (IZhO14_shymbulak)	C++14	0 / 100	1573 ms	6992 KiB

shymbulak

#include<bits/stdc++.h>
#include<ext/pb_ds/tree_policy.hpp>
#include<ext/pb_ds/assoc_container.hpp>

#define fi first
#define se second
#define new new228
#define pb push_back
#define rank rank228
#define sz(c) (int)(c).size()
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
 
using namespace std;
using namespace __gnu_pbds;
 
#pragma GCC optimize("Ofast")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,popcnt,abm,mmx,tune=native")
#pragma GCC optimize("fast-math")
#pragma warning(disable : 4996)
 
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set; // st.oreder_of_key();

const int N = 100100;
const int INF = 1e9 + 7;
const int MAXN = 4 * N;
const int MOD = 998244353;
 
int TN = 1;

int n;
int ans;
int d[N], us[N];
vector<int> verr[N];
set<pair<int, int>> st;

void solve() {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        int x, y;
        scanf("%d %d", &x, &y);
        verr[x].pb(y); verr[y].pb(x);
    }
    queue<int> q; q.push(1); us[1] = 1;
    int root = 1;
    while (!q.empty()) {
        int x = q.front(); q.pop();
        for (auto to: verr[x]) {
            if (!us[to]) {
                us[to] = true;
                d[to] = d[x] + 1;
                if (ans < d[to]) {
                    ans = d[to]; root = to;
                }
                q.push(to);
            }
        }
    }
    fill(d + 1, d + 1 + n, 0); fill(us + 1, us + 1 + n, 0);
    q.push(root); us[root] = 1;
    int cur = 0;
    while (!q.empty()) {
        int x = q.front(); q.pop();
        for (auto to: verr[x]) {
            if (!us[to]) {
                us[to] = true;
                d[to] = d[x] + 1;
                if (ans < d[to]) {
                    ans = d[to]; cur = 1;
                }
                else if (ans == d[to]) {
                    cur++;
                }
                q.push(to);
            }
        }
    }
    // printf("max shortest's len is %d\n", ans);
    int mx = 0;
    int cnt = 0;
    for (int i = 1; i <= n; i++) {
        fill(d + 1, d + 1 + n, 0);
        fill(us + 1, us + 1 + n, 0);
        q.push(i); us[i] = true; cnt = 0;
        while (!q.empty()) {
            int x = q.front(); q.pop();
            for (auto to: verr[x]) {
                if (!us[to]) {
                    d[to] = d[x] + 1;
                    if (d[to] == ans) {
                        cnt++;
                    } else {
                        q.push(to);
                    }
                    us[to] = 1;
                } else {
                    if (d[to] == ans) {
                        cnt++;
                    }
                    else if (d[x] > d[to]) {
                        continue;
                    }
                    else if (d[x] < d[to]) {
                        q.push(to);
                    }
                }
            }
        }
        // printf("%d %d\n", i, cnt);
        mx += cnt;
    }
    cout << mx / 2 << "\n";
    return;
}

signed main() {
    // ios_base::sync_with_stdio(0);
    // in; out;  // cin >> TN;
    while (TN--) { solve(); }
    return 0;
 }

Compilation message (stderr)

shymbulak.cpp:22:0: warning: ignoring #pragma warning  [-Wunknown-pragmas]
 #pragma warning(disable : 4996)
 
shymbulak.cpp: In function 'void solve()':
shymbulak.cpp:40:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
shymbulak.cpp:43:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &x, &y);
         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50