codeforce790div4-EFG

F. Longest Strike

思路：双指针统计区间个数，注意越界情况

#pragma GCC optimize(2)
#pragma GCC optimize(1)
#include<bits/stdc++.h> 
typedef long long ll;
typedef unsigned long long ull;
const ull base=131;
#define MAX 200009
#define PI 3.141592653589793
using namespace std;
int mm[MAX];
inline void solve(){
    int len,k;
    cin>>len>>k;
    map<int,int> check;
    for(int i=1;i<=len;i++){
        cin>>mm[i];check[mm[i]]++;
    }
    vector<int> op;
    for(auto x:check){
        if((x.second)>=k) op.push_back((x.first));
    }
    if(op.size()==0){
        cout<<-1<<"\n";return ;
    }
    sort(op.begin(),op.end());
    int olen=op.size(),l=0,r=1,men=0,tl=op[0],tr=op[0],tlen=1;
    for(;r<olen;r++){
        if(op[r]==op[r-1]+1){
            tlen++;
            if(tlen>men){
                men=tlen;
                tl=op[l];tr=op[r];
            }
        }
        else{
            tlen=1;l=r;
        }
    }
    cout<<tl<<' '<<tr<<endl;
}
int main(){
    int sum;cin>>sum;
    while(sum--){
        solve();
    }
}

E

思路：二分加贪心

#pragma GCC optimize(2)
#pragma GCC optimize(1)
#include<bits/stdc++.h> 
typedef long long ll;
typedef unsigned long long ull;
const ull base=131;
#define MAX 150009
#define PI 3.141592653589793
using namespace std;
int meme[MAX],pre[MAX];
bool cmp(int a,int b){
    return a>b;
}
inline void solve(){
    int len,k;cin>>len>>k;
    for(int i=1;i<=len;i++) cin>>meme[i];
    sort(meme+1,meme+len+1,cmp);
    for(int i=1;i<=len;i++) pre[i]=pre[i-1]+meme[i];
    for(int i=0;i<k;i++){
       int temp;cin>>temp;
       int check=lower_bound(pre+1,pre+1+len,temp)-pre;
       if(check==len+1) cout<<-1<<"\n";
       else cout<<check<<"\n";
    }
}
int main(){
    int sum;cin>>sum;
    while(sum--){
        solve();
    }
}

G

思路：有向图建树，利用dfs回溯统计树的平衡状态

#pragma GCC optimize(2)
#pragma GCC optimize(1)
#include<bits/stdc++.h> 
typedef long long ll;
typedef unsigned long long ull;
const ull base=131;
#define MAX 150009
#define PI 3.141592653589793
using namespace std;
int ans;
vector<int> edge[MAX];
char color[MAX];
int dfs(int fa,int now){
    int value;if(color[now]=='B') value=-1;else value=1;
    if(fa==now) return 0;
    for(auto y:edge[now]){
        value+=dfs(now,y);
    }
    if(value==0) ans++;
    return value;
}
inline void solve(){
    int fa;
    int len;cin>>len;
    for(int i=2;i<=len;i++){
        int temp;scanf("%d",&temp);
        edge[temp].push_back(i);
        if(i==temp) fa=i;
    }
    getchar();
    scanf("%s",color+1);
    ans=0;
    dfs(0,1);
    cout<<ans<<endl;
    for(int i=1;i<=len;i++)
    edge[i].clear();
}
int main()
{
    int sum;scanf("%d",&sum);
    while(sum--){
        solve();
    }
}