Submission #140269

#	Time	Username	Problem	Language	Result	Execution time	Memory
140269		ae04071	Necklace (Subtask 1-3) (BOI19_necklace1)	C++11	85 / 85	391 ms	508 KiB

necklace

#include <bits/stdc++.h>
using namespace std;

int n,m;
char s[3010],t[3010];

int pi[3010],fm[3010],bm[3010];

void getpi() {
    int i=0;
    for(int j=1;j<m;j++) {
        while(i && t[i]!=t[j]) i = pi[i-1];
        if(t[i]==t[j]) pi[j]=++i;
    }
}
void kmp(int *arr) {
    int j=0;
    for(int i=0;i<n;i++) {
        while(j && s[i]!=t[j]) {
            j = pi[j-1];
        }
        if(s[i]==t[j]) {
            ++j;
            if(j==m) {
                j=pi[j-1];
            }
        }
        arr[i] = j;
    }
}

int ans=0,ai,aj,f;
void solve() {
    for(int i=0;i<m;i++) {
        getpi();
        kmp(fm);

        reverse(s, s+n);
        reverse(t, t+m);
        getpi();
        kmp(bm);

        reverse(s, s+n);
        reverse(t,t+m);
        reverse(bm, bm+n);

        for(int j=0;j<n-1;j++) {
            int v = min(fm[j],m-i) + min(bm[j+1],i);
            if(ans < v) {
                ans = v;
                ai = j - fm[j] + 1;
                if(!f) aj = i - min(bm[j+1], i);
                else aj = m-i - min(fm[j], m-i);
            }
        }

        char ch = t[0];
        for(int j=0;j<m-1;j++) t[j]=t[j+1];
        t[m-1]=ch;
    }
}
int main() {
    scanf("%s%s",s,t);
    n=strlen(s);
    m=strlen(t);

    solve();
    f=1;
    reverse(t,t+m);
    solve();

    printf("%d\n%d %d\n",ans,ai,aj);

    return 0;
}

Compilation message (stderr)

necklace.cpp: In function 'int main()':
necklace.cpp:63:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s%s",s,t);
     ~~~~~^~~~~~~~~~~~

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