为何此题不可暴力？蒟蒻求救

#include<iostream>
using namespace std;
int n,m;
int a[2000001]={0},minn;
int main(){
    cin>>n>>m;
    for(long i=1;i<=n;i++)cin>>a[i];
    for(long i=1;i<=n;i++)
    {
        if(i==1){
            cout<<"0"<<endl;
            continue;
        }
        minn=0x7fffffff;
        for(int j=i-1;j>=i-m;j--){
            if(j>=1)
            if(minn>a[j])minn=a[j];
        }
        cout<<minn<<endl;
    }
    return 0;
}