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Submission #819721

# Submission time Handle Problem Language Result Execution time Memory
819721 2023-08-10T12:57:29 Z isaachew Palindromic Partitions (CEOI17_palindromic) C++17
100 / 100
 4590 ms 27176 KB 
#include <bits/stdc++.h>

/*
 Use hashing
 
 AAAAAAA  AAAAAAA
 BBBB        BBBB
 ABCABCA  ABCABCA
 -> A BC A BC A (rotations)
 
 
 ABCDEABCDEABC -> ABC DE ABC DE ABC, original is not solution
 
 Greedy works
 
 
 
 */

int n,t;
int hashbase;
int hashmod=1000000007;
long long binexp(int a,int b,int mod=hashmod){
    b=(b%(mod-1)+(mod-1))%(mod-1);
    long long e=a;
    long long s=1;
    while(b){
        if(b&1)s*=e;
        s%=mod;
        e=e*e%mod;
        b>>=1;
    }
    return s;
}
int main(){
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(0);
    std::mt19937 rgen(std::chrono::steady_clock().now().time_since_epoch().count());
    std::cin>>t;
    for(;t--;){
        hashbase=std::uniform_int_distribution(100000000,1000000006)(rgen);
        std::string s;
        std::cin>>s;
        n=s.size();
        std::vector<long long> hashes(1);
        long long chash=0;
        for(int i=0;i<n;i++){
            chash+=s[i]*binexp(hashbase,i,hashmod);
            chash%=hashmod;
            hashes.push_back(chash);
        }
        int progress=0;
        int last=0;
        int total=1;
        for(int i=1;i*2<=n;i++){
            long long hash1=(hashes[i]-hashes[progress]+hashmod)%hashmod*binexp(hashbase,(n-i)-progress,hashmod)%hashmod;
            long long hash2=(hashes[n-progress]-hashes[n-i]+hashmod)%hashmod;
            //std::cout<<hash1<<' '<<hash2<<'\n';
            if(hash1==hash2){
                //std::cout<<i-progress<<'\n';
                progress=i;
                total+=2;
                if(i*2==n)total--;//no substr in between
            }
        }
        std::cout<<total<<'\n';
    }
    return 0;
}

Compilation message

palindromic.cpp: In function 'int main()':
palindromic.cpp:53:13: warning: unused variable 'last' [-Wunused-variable]
   53 |         int last=0;
      |             ^~~~

Subtask #1
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 320 KB Output is correct
5 Correct 1 ms 212 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 320 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 320 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct

Subtask #3
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 320 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 320 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 31 ms 628 KB Output is correct
11 Correct 17 ms 584 KB Output is correct
12 Correct 30 ms 628 KB Output is correct
13 Correct 25 ms 600 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 320 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 320 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 31 ms 628 KB Output is correct
11 Correct 17 ms 584 KB Output is correct
12 Correct 30 ms 628 KB Output is correct
13 Correct 25 ms 600 KB Output is correct
14 Correct 4590 ms 27176 KB Output is correct
15 Correct 2440 ms 21656 KB Output is correct
16 Correct 4375 ms 26376 KB Output is correct
17 Correct 2356 ms 18708 KB Output is correct