Submission #129976

#	Time	Username	Problem	Language	Result	Execution time	Memory
129976		TadijaSebez	Palindromic Partitions (CEOI17_palindromic)	C++11	100 / 100	244 ms	22812 KiB

palindromic

#include <stdio.h>
#include <algorithm>
#include <vector>
#include <cstring>
using namespace std;
#define pb push_back
#define mp make_pair
#define ll long long
const int mod=998244353;
const int N=1000050;
int hs[N],po[N],ip[N];
int pow(int x, int k)
{
    int ret=1;
    for(;k;k>>=1,x=(ll)x*x%mod) if(k&1) ret=(ll)ret*x%mod;
    return ret;
}
void preprocess()
{
    int i;
    po[0]=1;
    for(i=1;i<N;i++) po[i]=(ll)po[i-1]*26%mod;
    int mul=pow(26,mod-2);
    ip[0]=1;
    for(i=1;i<N;i++) ip[i]=(ll)ip[i-1]*mul%mod;
}
char s[N];
void Build(int n)
{
    int i;
    for(i=1;i<=n;i++)
    {
        hs[i]=(ll)hs[i-1]*26%mod+(s[i]-'a'+1);
        hs[i]%=mod;
    }
}
int GetHash(int l, int r)
{
    int ret=hs[r]-(ll)hs[l-1]*po[r-l+1]%mod;
    if(ret<0) ret+=mod;
    return ret;
}
bool Compare(int l1, int r1, int l2, int r2)
{
    return GetHash(l1,r1)==GetHash(l2,r2);
}
int main()
{
    preprocess();
    int t;
    scanf("%i",&t);
    while(t--)
    {
        scanf("%s",s+1);
        int n=strlen(s+1);
        Build(n);
        int sol=0,i,j=1;
        for(i=1;i<=n-j+1;i++)
        {
            if(Compare(j,i,n-i+1,n-j+1))
            {
                sol++;
                if(i!=n-j+1) sol++;
                //printf("%i %i\n",j,i);
                j=i+1;
            }
        }
        printf("%i\n",sol);
        for(i=1;i<=n;i++) s[i]=0;
    }
    return 0;
}

Compilation message (stderr)

palindromic.cpp: In function 'int main()':
palindromic.cpp:51:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%i",&t);
     ~~~~~^~~~~~~~~
palindromic.cpp:54:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%s",s+1);
         ~~~~~^~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 40 / 40