2025-11-24

CF

构造（1300）

Problem - 1889A - Codeforces

#include <bits/stdc++.h>
using namespace std;
#define LL long long
const LL mod = 998244353;
const int N=2e5+10;void add(string &s,int x){//在第 x个字符前加入s = s.substr(0, x) + "01" +s.substr(x);
}void solve()
{int n;cin >> n;string s;cin >> s;vector<int> cnt(2);for (int i = 0; i < n;i++){cnt[s[i] - '0']++;}if(cnt[0]!=cnt[1]){cout << -1 << endl;return;}vector<int> a;for (int i = 0; i < s.size();i++){int t = s.size() - i - 1;if(s[i]!=s[t])continue;if(s[i]=='0'){add(s, t + 1);a.push_back(t + 1);}else{add(s, i);a.push_back(i);}if(a.size()>300)break;}if(a.size()>300){cout << -1 << endl;return;}cout << a.size() << endl;for (int i = 0; i < a.size();i++){cout << a[i] << " ";}cout << endl;
}int main()
{ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);int T;cin >> T;while (T--){solve();}
}

Problem - 1882B - Codeforces(bitset)

#include <bits/stdc++.h>
using namespace std;
#define LL long long
const LL mod = 998244353;
const int N=55;
bitset<N> s[N], U;void solve()
{int n;cin >> n;U.reset();//清零for (int i = 1; i <= n;i++){s[i].reset();}for (int i = 1; i <= n;i++){int k;cin >> k;for (int j = 1; j <= k;j++){int x;cin >> x;s[i][x] = 1;}U |= s[i];}int ans = 0;for (int i = 1; i <= 50;i++){if(U[i]==0)continue;bitset<N> now;for (int j = 1; j <= n;j++){//遍历每个集合if(s[j][i]==0)now |= s[j];}ans = max(ans, (int)now.count());}cout << ans << endl;
}int main()
{ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);int T;cin >> T;while (T--){solve();}
}

Problem - 1868A - Codeforces

#include <bits/stdc++.h>
using namespace std;
#define LL long long
const LL mod = 998244353;
const int N=2e5+10;void solve()
{int n,m;cin >> n >> m;vector<vector<int>> a(n, vector<int>(m));for (int i = 0; i < min(m - 1, n);i++){for (int j = 0; j < m;j++){a[i][(i + j) % m] = j;}}for (int i = m - 1; i < n;i++){for (int j = 0; j < m;j++){a[i][j] = j;}}if (n<m){cout << n + 1 << endl;}else if(m==1){cout << 0 << endl;}else{cout << m << endl;}for (int i = 0; i < n;i++){for (int j = 0; j < m;j++){cout << a[i][j] << " ";}cout << endl;}
}int main()
{ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);int T;cin >> T;while (T--){solve();}
}