题解 | 而后单调

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

int main() {
    int T;
    cin >> T;
    while(T--){
        int n, m;
        cin >> n >> m;
        vector<int> a(n);
        vector<int> b(n);
        unordered_set<int> mark;
        bool flag = false;
        for(int i=0; i<n; ++i){
            cin >> a[i];
            b[i] = a[i];
            if(mark.count(a[i])){
                flag = true;
            }
            mark.insert(a[i]);
        }
        if(flag){
            cout << "NO" << endl;
            continue;
        }
        sort(b.begin(), b.end());
        unordered_map<int, int> f;
        bool flag1 = false;
        for(int i=0; i<n; ++i)
            f[b[i]] = i;
        for(int i=0; i+m <= n; ++i){
            int j = i+1;
            while(f[a[j]]-1 == f[a[j-1]]) ++j;
            if(j-i>=m){
                flag1 = true;
                break;
            }
        }
        if(flag1){
            cout << "YES" <<endl;
            continue;
        }
        reverse(b.begin(), b.end());
        bool flag2 = false;
        for(int i=0; i<n; ++i)
            f[b[i]] = i;
        for(int i=0; i+m <= n; ++i){
            int j = i+1;
            while(f[a[j]]-1 == f[a[j-1]]) ++j;
            if(j-i>=m){
                flag2 = true;
                break;
            }
        }
        if(flag2){
            cout << "YES" <<endl;
        }else{
            cout << "NO" << endl;
        }
    }

    return 0;
}
// 64 位输出请用 printf("%lld")