Submission #156145

#	Time	Username	Problem	Language	Result	Execution time	Memory
156145		Flying_dragon_02	전압 (JOI14_voltage)	C++14	100 / 100	242 ms	18028 KiB

voltage

#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define pb push_back
#define mp make_pair

typedef pair<int, int> ii;

const int mod = 1e9 + 7;

const int inf = 1e9;

int add(int x, int y) {
    return (1ll * x + 1ll * y) % mod;
}

int del(int x, int y) {
    return ((1ll * x - 1ll * y) % mod + mod) % mod;
}

int mul(int x, int y) {
    return (1ll * x * 1ll * y) % mod;
}

const int N = 2e5 + 5;

int n, m, bad[N], badEdge, ans, parity[N], dist[N], low[N];

vector<ii> graph[N];

bool vis[N], used[N];

int cnt;

void dfs(int u, int p) {
    dist[u] = low[u] = ++cnt;
    parity[u] = parity[p] ^ 1;
    for(int i = 0; i < graph[u].size(); i++) {
        int v = graph[u][i].fi, id = graph[u][i].se;
        if(used[id]) continue;
        used[id] = 1;
        if(!dist[v]) {
            dfs(v, u);
            bad[u] += bad[v];
            low[u] = min(low[u], low[v]);
        }
        else {
            if(parity[v] == parity[u]) {
                if(dist[v] < dist[u]) {
                    bad[v]--;
                    bad[u]++;
                    badEdge++;
                }
            }
            else
                low[u] = min(low[u], dist[v]);
        }
    }
}

void bfs(int u, int p) {
    vis[u] = 1;
    for(int i = 0; i < graph[u].size(); i++) {
        int v = graph[u][i].fi;
        if(v == p) continue;
        if(!vis[v]) {
            bfs(v, u);
            //cout << u << " " << v << " " << low[v] << " " << dist[u] << "\n";
            if(bad[v] == badEdge && low[v] > dist[u])
            ans++;
        }
    }
}

int main() {
    cin.tie(0), ios_base::sync_with_stdio(0);
    cin >> n >> m;
    for(int i = 1; i <= m; i++) {
        int u, v;
        cin >> u >> v;
        graph[u].pb({v, i});
        graph[v].pb({u, i});
    }
    for(int i = 1; i <= n; i++) {
        if(!dist[i])
            dfs(i, i);
    }
    if(badEdge == 1)
        ans++;
    memset(vis, 0, sizeof(vis));
    for(int i = 1; i <= n; i++) {
        if(!vis[i])
            bfs(i, i);
    }
    cout << ans;
}

Compilation message (stderr)

voltage.cpp: In function 'void dfs(int, int)':
voltage.cpp:41:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < graph[u].size(); i++) {
                    ~~^~~~~~~~~~~~~~~~~
voltage.cpp: In function 'void bfs(int, int)':
voltage.cpp:66:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < graph[u].size(); i++) {
                    ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 35 / 35
• Subtask 4: 45 / 45