LongestRepeatSubStringMap

#include<stdio.h>
#include<map>
using namespace std;
typedef long long int ll;
ll const Pr = 98765431;

ll mpow(ll a,ll b){
    ll ta = a;
    if(b == 0)return 1;
    for(int i = 1 ; i < b ; i ++){
        ta *= a;
    }
    return ta;
}

int main()
{
    int n,m;
    scanf("%d %d",&n,&m);
    char str[n+1];
    scanf("%s",str);
    int L = 1 , R = n;
    int ans = 0;
    while(L <= R){
        int size = (L+R)/2;
        map<ll,int> table;table.clear();
        ll mp = mpow(Pr,size-1);
        ll hs = 0;
        ll maxRe = 0;
    //  printf("Test size : %d ",size);
        for(int i = 0 ; i < n && maxRe < m ; i ++){
            hs *= Pr;
            hs += str[i];
            if(i >= size - 1){
                if(table.count(hs)){ //Repeat
                    table[hs]++;
                }
                else{ //new
                    table.insert({hs,1});
                }
                if(table[hs] > maxRe)maxRe = table[hs];
                hs -= mp*str[i-size+1];
            }
        }
    //  printf(", maxRe = %d\n",maxRe);
        if(maxRe >= m){
            ans = size;
            L = size + 1;
        }
        else{
            R = size - 1;
        }
    }
    printf("%d",ans);
    return 0;
}