1.十六進制

#include<bits/stdc++.h>
using namespace std;int n;int main(){cin>>n;stack<int>re;if(n<16)cout<<0;while(n){re.push(n%16);n/=16;}while(!re.empty()){int x=re.top();re.pop();if(x<10)cout<<x;else cout<<char('A'+x-10);}return 0;
}

2.游戲

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=1e5+10;int t,n;int main(){ios::sync_with_stdio(false);cin>>t;while(t--){vector<pair<ll,ll>>p;cin>>n;for(int i=0;i<n;++i){ll a,b;cin>>a>>b;p.push_back({a,b});			}sort(p.begin(),p.end());ll ans=p[0].first;for(int i=1;i<n;++i){ll a=p[i-1].second-p[i].second;ll b=p[i].first-p[i-1].first;ans+=min(a,b);}ans+=p[n-1].second;cout<<ans<<'\n';}return 0;
}

4.染色

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=4e5+10;int t;
int n,a;
ll sum;int main(){ios::sync_with_stdio(false);cin>>t;while(t--){sum=0;cin>>n;for(int i=0;i<n;++i){cin>>a;sum+=a;}if(n<2||sum%2!=0){cout<<0<<'\n';continue;}else cout<<n*(n-1)/2<<'\n';}return 0;
}

5。不要回文

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=3e5+10;int q,n;
string s;int main(){cin>>q;while(q--){cin>>n>>s;int c[30]{0};for(auto i:s)c[i-'a']++;vector<int>who;for(int i=0;i<26;++i){if(c[i])who.push_back(c[i]);}sort(who.begin(),who.end());int l=0,f=1;for(auto i:who){//cout<<i<<" ";if(i>max(l/2+1,0)){f=0;break;}l+=i;}if(f)cout<<"Yes\n";else cout<<"No\n";		}return 0;
}

6.面包

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=3e5+10;int n;
ll d,p,r,sum=0;
vector<array<ll,3>>who;int main(){cin>>n;for(int i=1;i<=n;++i){cin>>d>>p>>r;who.push_back({d,i,1});who.push_back({p,i,2});who.push_back({r,i,3});}sort(who.begin(),who.end());int c[N]{0},t=0,q[4]{0};for(int i=who.size()-1;i>=0;--i){auto x=who[i];if(t==n){sum+=x[0];}else if(c[x[1]]==0){if(3-q[1]-q[2]-q[3]>=n-t&&q[x[2]]){sum+=x[0];}else{c[x[1]]=1;t++;q[x[2]]=1;}}else{sum+=x[0];}}cout<<sum;return 0;
}