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Submission #367375

# Submission time Handle Problem Language Result Execution time Memory
367375 2021-02-17T03:01:35 Z GusMG Necklace (Subtask 1-3) (BOI19_necklace1) C++17
85 / 85
 235 ms 768 KB 
#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define per(i,a,b) for(int i=(b)-1;i>=(a);i--)
using ll=long long;
using vi=vector<int>;
//pi[i] = longitud del prefijo propio mas grande de s[0..i] que tambien es sufijo
vi prefix_function(string s) {
    vi pi(s.size());
    for(int i=1,j=0; i<s.size(); i++) {
        while(j && s[i]!=s[j]) j=pi[j-1];
        if(s[i]==s[j]) j++;
        pi[i] = j;
    }
    return pi;
}
// Busca las coincidencias de p en s, regresa indices de inicio
vi kmp(string s, string p) {
    vi pi = prefix_function(p);
    vi ans(s.size());
    for(int i=0,j=0; i<s.size(); i++) {
        while(j && s[i]!=p[j]) j=pi[j-1];
        if(s[i]==p[j]) j++;
        ans[i]=j;
        if(j==p.size()) {
            j=pi[j-1];
        }
    }
    return ans;
}
int main(){
    ios_base::sync_with_stdio(0);
    string s,t;
    cin>>s>>t;
    int n=s.size(),m=t.size(),ans=0,l=0,r=0;
    string s2=s,t2=t;
    reverse(s2.begin(),s2.end());
    reverse(t2.begin(),t2.end());
    rep(i,1,n) {
        vi lps=kmp(t,s.substr(i)),lsp=kmp(t2,s2.substr(n-i));
        rep(j,0,m-1) {
            int a=lps[j],b=lsp[m-j-2];
            if(ans<a+b) ans=a+b,l=i-b,r=j-a+1;
        }
        lps=kmp(t,s2.substr(i)),lsp=kmp(t2,s.substr(n-i));
        rep(j,0,m-1) {
            int a=lps[j],b=lsp[m-j-2];
            if(ans<a+b) ans=a+b,l=n-i-a,r=j-a+1;
        }
    }
    cout<<ans<<"\n";
    cout<<l<<" "<<r<<"\n";
}

Compilation message

necklace.cpp: In function 'vi prefix_function(std::string)':
necklace.cpp:10:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |     for(int i=1,j=0; i<s.size(); i++) {
      |                      ~^~~~~~~~~
necklace.cpp: In function 'vi kmp(std::string, std::string)':
necklace.cpp:21:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |     for(int i=0,j=0; i<s.size(); i++) {
      |                      ~^~~~~~~~~
necklace.cpp:25:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |         if(j==p.size()) {
      |            ~^~~~~~~~~~

Subtask #1
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 6 ms 364 KB Output is correct
7 Correct 4 ms 364 KB Output is correct
8 Correct 5 ms 364 KB Output is correct
9 Correct 4 ms 364 KB Output is correct
10 Correct 4 ms 364 KB Output is correct
11 Correct 4 ms 364 KB Output is correct
12 Correct 4 ms 364 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 6 ms 364 KB Output is correct
7 Correct 4 ms 364 KB Output is correct
8 Correct 5 ms 364 KB Output is correct
9 Correct 4 ms 364 KB Output is correct
10 Correct 4 ms 364 KB Output is correct
11 Correct 4 ms 364 KB Output is correct
12 Correct 4 ms 364 KB Output is correct
13 Correct 224 ms 620 KB Output is correct
14 Correct 187 ms 492 KB Output is correct
15 Correct 235 ms 492 KB Output is correct
16 Correct 194 ms 492 KB Output is correct
17 Correct 163 ms 492 KB Output is correct
18 Correct 176 ms 492 KB Output is correct
19 Correct 175 ms 492 KB Output is correct
20 Correct 206 ms 768 KB Output is correct
21 Correct 203 ms 548 KB Output is correct