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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#256839#7755. Game on a Forestucup-team1951#WA 4ms12468kbC++173.7kb2023-11-18 22:10:412023-11-18 22:10:43

Judging History

你现在查看的是最新测评结果

  • [2023-11-18 22:10:43]
  • 评测
  • 测评结果:WA
  • 用时:4ms
  • 内存:12468kb
  • [2023-11-18 22:10:41]
  • 提交

answer

// g++-13 3.cpp -std=c++17 -O2 -I .
#include <bits/stdc++.h>
using namespace std;


#include <algorithm>
#include <cassert>
#include <vector>

namespace atcoder {

struct dsu {
  public:
    dsu() : _n(0) {}
    explicit dsu(int n) : _n(n), parent_or_size(n, -1) {}

    int merge(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        int x = leader(a), y = leader(b);
        if (x == y) return x;
        if (-parent_or_size[x] < -parent_or_size[y]) std::swap(x, y);
        parent_or_size[x] += parent_or_size[y];
        parent_or_size[y] = x;
        return x;
    }

    bool same(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        return leader(a) == leader(b);
    }

    int leader(int a) {
        assert(0 <= a && a < _n);
        if (parent_or_size[a] < 0) return a;
        return parent_or_size[a] = leader(parent_or_size[a]);
    }

    int size(int a) {
        assert(0 <= a && a < _n);
        return -parent_or_size[leader(a)];
    }

    std::vector<std::vector<int>> groups() {
        std::vector<int> leader_buf(_n), group_size(_n);
        for (int i = 0; i < _n; i++) {
            leader_buf[i] = leader(i);
            group_size[leader_buf[i]]++;
        }
        std::vector<std::vector<int>> result(_n);
        for (int i = 0; i < _n; i++) {
            result[i].reserve(group_size[i]);
        }
        for (int i = 0; i < _n; i++) {
            result[leader_buf[i]].push_back(i);
        }
        result.erase(
            std::remove_if(result.begin(), result.end(),
                           [&](const std::vector<int>& v) { return v.empty(); }),
            result.end());
        return result;
    }

  private:
    int _n;
    std::vector<int> parent_or_size;
};

}  // namespace atcoder

using namespace atcoder;

using ll = long long;
using ld = long double;
 
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vld = vector<ld>;
using vvld = vector<vld>;
using vst = vector<string>;
using vvst = vector<vst>;
 
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define pq_big(T) priority_queue<T,vector<T>,less<T>>
#define pq_small(T) priority_queue<T,vector<T>,greater<T>>
#define all(a) a.begin(),a.end()
#define rep(i,start,end) for(ll i=start;i<(ll)(end);i++)
#define per(i,start,end) for(ll i=start;i>=(ll)(end);i--)
#define uniq(a) sort(all(a));a.erase(unique(all(a)),a.end())

void dfs(int now,int par,vvi &g,vi &s0,vi &s1,vi &sz){
  for(int nxt:g[now]){
    if(nxt==par){
      continue;
    }
    dfs(nxt,now,g,s0,s1,sz);
    if(sz[nxt]%2==0){
      s0[now]++;
    }
    else{
      s1[now]++;
    }
    sz[now]+=sz[nxt];
  }

  sz[now]++;
  s0[now]%=2;
  s1[now]%=2;
  sz[now]%=2;
  return;
}

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int n,m;cin>>n>>m;
  dsu d(n);

  vector<pair<int,int>> e(m);
  vvi g(n);

  rep(i,0,m){
    int u,v;cin>>u>>v;
    u--;v--;
    e[i]={u,v};
    d.merge(u,v);
    g[u].emplace_back(v);
    g[v].emplace_back(u);
  }

  vvi v=d.groups();
  int grundy=0;
  for(vi vv:v){
    grundy^=(2-vv.size()%2);
  }

  vi s0(n,0),s1(n,0),sz(n,0);
  rep(i,0,n){
    if(sz[i]==0){
      dfs(i,-1,g,s0,s1,sz);
    }
  }

  int ans=0;
  rep(i,0,m){
    auto [u,v]=e[i];
    int g2=grundy;
    if(d.size(i)%2==0)g2^=2;
    if(g2==0){
      // cerr<<i<<" : "<<u<<" "<<v<<endl;
      ans++;
    }
  }

  rep(i,0,n){
    int g2=grundy;
    g2^=(2-d.size(i)%2);
    int remain=d.size(i)-sz[i];
    g2^=(2-remain%2);
    if(s0[i]){
      g2^=2;
    }
    if(s1[i]){
      g2^=1;
    }

    if(g2==0){
      // cerr<<i<<" : "<<i<<endl;
      ans++;
    }
  }

  cout<<ans<<endl;
}


/*
1-2 3 grundy 3
->
2 3 grundy 0
*/

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 0ms
memory: 3596kb

input:

3 1
1 2

output:

2

result:

ok 1 number(s): "2"

Test #2:

score: 0
Accepted
time: 0ms
memory: 3616kb

input:

4 3
1 2
2 3
3 4

output:

3

result:

ok 1 number(s): "3"

Test #3:

score: -100
Wrong Answer
time: 4ms
memory: 12468kb

input:

100000 1
4647 17816

output:

0

result:

wrong answer 1st numbers differ - expected: '1', found: '0'