Submission #156119

#	Time	Username	Problem	Language	Result	Execution time	Memory
156119		Flying_dragon_02	우호 조약 체결 (JOI14_friends)	C++14	100 / 100	123 ms	15612 KiB

friends

#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, pSet[N], sz[N];

vector<int> graph[N];

int findSet(int u) {
    //cout << u << "\n";
    if(u == pSet[u]) return u;
    else return pSet[u] = findSet(pSet[u]);
}

void unionSet(int u, int v) {
    u = findSet(u), v = findSet(v);
    if(u == v) return ;
    sz[v] += sz[u];
    pSet[u] = v;
}

bool vis[N];

vector<int> vec, gr[N];

queue<int> q;

void dfs() {
    while(!q.empty()) {
        int u = q.front();
        q.pop();
        for(int i = 0; i < graph[u].size(); i++) {
            int v = graph[u][i];
            if(!vis[v]) {
                vis[v] = 1;
                q.push(v);
            }
                unionSet(u, v);
        }
    }
}

int main() {
    cin.tie(0), ios_base::sync_with_stdio(0);
   // freopen("test.inp", "r", stdin);
    cin >> n >> m;
    for(int i = 1; i <= n; i++)
        pSet[i] = i, sz[i] = 1;
    for(int i = 1; i <= m; i++) {
        int u, v;
        cin >> u >> v;
        graph[u].pb(v);
    }
    for(int i = 1; i <= n; i++) {
        if(graph[i].size() >= 2) {
            for(int j = 0; j < graph[i].size() - 1; j++)
                unionSet(graph[i][j], graph[i][j + 1]);
        }
    }
    /*for(int i = 1; i <= n; i++) {
        for(int j = 0; j < graph[i].size(); j++) {
            int v = graph[i][j];
            if(findSet(i) != findSet(v))
                gr[findSet(i)].pb(findSet(v));
        }
    }
    for(int i = 1; i <= n; i++) {
        graph[i] = gr[i];
        gr[i].clear();
    }*/
    for(int i = 1; i <= n; i++) {
        if(sz[findSet(i)] >= 2)
            q.push(i), vis[i] = 1;
    }
    dfs();
    /*for(int i = 1; i <= n; i++) {
        for(int j = 0; j < graph[i].size(); j++) {
            int v = graph[i][j];
            if(findSet(i) != findSet(v))
                gr[findSet(i)].pb(findSet(v));
        }
    }
    for(int i = 1; i <= n; i++)
        graph[i] = gr[i];*/
    memset(vis, 0, sizeof(vis));
    long long total = 0;
    for(int i = 1; i <= n; i++) {
        if(!vis[findSet(i)]) {
            vis[findSet(i)] = 1;
            if(sz[findSet(i)] >= 2)
                total += 1ll * sz[findSet(i)] * (sz[findSet(i)] - 1);
            else
                total += graph[findSet(i)].size();
        }
    }
    cout << total;
}

Compilation message (stderr)

friends.cpp: In function 'void dfs()':
friends.cpp:57:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < graph[u].size(); i++) {
                        ~~^~~~~~~~~~~~~~~~~
friends.cpp: In function 'int main()':
friends.cpp:81:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int j = 0; j < graph[i].size() - 1; j++)
                            ~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 30 / 30
• Subtask 3: 65 / 65