题解 | 而后单调

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;


int main() {
    int t;
    cin>>t;
    while(t--){
        int n,m;
        cin>>n>>m;
        vector<pair<int,int>> a;
        for(int i=0;i<n;i++){
            int x;
            cin>>x;
            a.push_back({x,i});
        }
        sort(a.begin(), a.end());
        bool flag = true;
        int maxlen=1, nowlen1 = 1, nowlen2 = 1;
        for(int i=1;i<a.size();i++){
            if(a[i].first==a[i-1].first){
                flag = false;
                break;
            }
            if(a[i].second-1==a[i-1].second){
                nowlen1 ++;
                maxlen = max(maxlen, nowlen1);
            }else{
                nowlen1 = 1;
            }
            if(a[i].second+1 == a[i-1].second){
                nowlen2++;
                maxlen = max(maxlen, nowlen2);
            }else{
                nowlen2 = 1;
            }
        }
        if(!flag || maxlen<m)
            cout<<"NO"<<endl;
        else
            cout<<"YES"<<endl;
    }
}