Submission #885031

#	Time	Username	Problem	Language	Result	Execution time	Memory
885031		patrikpavic2	Palindromes (APIO14_palindrome)	C++17	100 / 100	90 ms	84692 KiB

palindrome

#include <algorithm>
#include <vector>
#include <cstdio>
#include <cstring>
 
#define PB push_back
 
using namespace std;
 
typedef long long ll;
 
const int N = 3e5 + 500;
const int INF = 0x3f3f3f3f;
 
struct node{
    node* CH[30];
    node* bk;
    int len, cnt;
} *n0, *n1;
 
bool cmp(node* X, node* Y){
    return X -> len > Y -> len;
}
 
char s[N];
int n;
ll mx;
vector < node* > v;
 
void precompute(){
    n1 = new node(); n0 = new node();
    n1 -> len = -1, n0 -> len = 0;
    n0 -> bk = n1; n1 -> bk = n1;
    node* cur = n0;
    for(int i = 0;i < n;i++){
        for(; cur->len + 1 > i || s[i - cur->len - 1] != s[i]; cur = cur -> bk);
        node *rmb = cur -> bk;
        if(cur -> CH[s[i] - 'a'] == NULL)
            cur -> CH[s[i] - 'a'] = new node(), v.PB(cur -> CH[s[i] - 'a']);
        cur -> CH[s[i] - 'a'] -> len = cur -> len + 2;
        cur = cur -> CH[s[i] - 'a'];
        cur -> cnt++;
        //printf("len = %d\n", cur -> len);
        for(; rmb -> len + 1 > i || s[i - rmb->len - 1] != s[i]; rmb = rmb -> bk);
        if(cur -> len == 1)
            cur -> bk = n0;
        else{
            if(rmb -> CH[s[i] - 'a'] == NULL)
                rmb -> CH[s[i] - 'a'] = new node(), v.PB(rmb -> CH[s[i] - 'a']);
            cur -> bk = rmb -> CH[s[i] - 'a'];
        }
        //printf("bk = %d\n", cur -> bk -> len);
    }
}
 
 
 
int main(){
    scanf("%s", s);
    n = strlen(s);
    precompute();
    sort(v.begin(), v.end(), cmp);
    for(int i = 0;i < v.size();i++){
        mx = max(mx, (ll)v[i] -> len * v[i] -> cnt);
        v[i] -> bk -> cnt += v[i] -> cnt;
    }
    printf("%lld\n", mx);
}

Compilation message (stderr)

palindrome.cpp: In function 'int main()':
palindrome.cpp:63:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<node*>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |     for(int i = 0;i < v.size();i++){
      |                   ~~^~~~~~~~~~
palindrome.cpp:59:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |     scanf("%s", s);
      |     ~~~~~^~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 26 / 26
• Subtask 5: 27 / 27