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Submission #71753

# Submission time Handle Problem Language Result Execution time Memory
71753 2018-08-25T14:26:40 Z evpipis Palindromes (APIO14_palindrome) C++11
73 / 100
 1000 ms 24540 KB 
#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
typedef long long ll;
typedef pair<int, int> ii;

const int len = 3e5+5, mod = 1e9+7, base = 57;
int suf[len], has1[len], has2[len], po[len], lim[len], n, lef[len], rig[len];
char str[len];
vector<int> vec[len];
vector<ii> st;
set<int> mys;

inline int add(int a, int b){
    a += b;
    if (a >= mod) a -= mod;
    return a;
}

inline int sub(int a, int b){
    a -= b;
    if (a < 0) a += mod;
    return a;
}

int mul(int a, int b){
    return (a*1LL*b)%mod;
}

inline int val1(int l, int r){
    l++, r++;
    return sub(has1[r], mul(has1[l-1], po[r-l+1]));
}

inline int val2(int l, int r){
    return (sub(has2[l], mul(has2[r+1], po[r-l+1])));
}

int lcp(int a, int b){
    int l = 1, r = n-1-max(a, b)+1, ans = 0;
    while (l <= r){
        int mid = (l+r)/2;
        if (val1(a, a+mid-1) == val1(b, b+mid-1))
            ans = mid, l = mid+1;
        else
            r = mid-1;
    }

    return ans;
}

bool comp(int a, int b){
    int c = lcp(a, b);
    return (str[a+c] < str[b+c]);
}

int bs(int i, int t){
    int l = 1, r = min(n-i-t, i+1), ans = 0;
    while (l <= r){
        int mid = (l+r)/2;
        if (val1(i-mid+1, i+t+mid-1) == val2(i-mid+1, i+t+mid-1))
            ans = 2*mid - (1-t), l = mid+1;
        else
            r = mid-1;
    }

    return ans;
}

int main(){
    scanf("%s", &str);
    n = strlen(str);
    str[n] = 0;

    po[0] = 1;
    for (int i = 1; i <= n; i++)
        po[i] = mul(po[i-1], base);
    for (int i = 1; i <= n; i++)
        has1[i] = add(mul(has1[i-1], base), str[i-1]-'a');
    for (int i = n-1; i >= 0; i--)
        has2[i] = add(mul(has2[i+1], base), str[i]-'a');

    for (int i = 0; i < n; i++)
        suf[i] = i;
    sort(suf, suf+n, comp);

    for (int i = 0; i < n; i++)
        lim[i] = -1;
    for (int i = 0; i < n-1; i++)
        lim[suf[i]] = lcp(suf[i], suf[i+1]);

    //for (int i = 0; i < n; i++)
      //  printf("%d ", suf[i]);
    //printf("\n");

    ll ans = 0;
    for (int i = 0; i < n; i++){
        int temp = bs(i, 0);
        vec[i-temp/2].pb(temp);
        ans = max(ans, (ll)temp);

        //printf("i = %d, mx0 = %d\n", i, temp);

        temp = bs(i, 1);
        vec[i-temp/2+1].pb(temp);
        ans = max(ans, (ll)temp);

        //printf("i = %d, mx1 = %d\n", i, temp);
    }

    int k = 0;
    for (int i = 0; i < n; i++){
        for (int j = 0; j < vec[i].size(); j++)
            mys.insert(vec[i][j]-k);

        set<int>::iterator it = mys.upper_bound(lim[i]-k);
        if (lim[i] != -1 && it != mys.begin()){
            it = prev(it);
            lim[i] = *it + k;
        }
        else
            lim[i] = 0;

        k-=2;
    }

    //for (int i = 0; i < n-1; i++)
      //  printf("%d ", lim[suf[i]]);
    //printf("\n");

    st.pb(mp(-1, -1));
    for (int i = 0; i < n-1; i++){
        while (lim[suf[i]] <= st.back().fi)
            st.pop_back();
        lef[i] = st.back().se;
        st.pb(mp(lim[suf[i]], i));
    }

    st.clear(), st.pb(mp(-1, n-1));
    for (int i = n-2; i >= 0; i--){
        while (lim[suf[i]] <= st.back().fi)
            st.pop_back();
        rig[i] = st.back().se;
        st.pb(mp(lim[suf[i]], i));
    }

    for (int i = 0; i < n-1; i++)
        ans = max(ans, lim[suf[i]] * 1LL * (rig[i]-lef[i]));
    printf("%lld\n", ans);
    return 0;
}

Compilation message

palindrome.cpp: In function 'int main()':
palindrome.cpp:75:21: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[300005]' [-Wformat=]
     scanf("%s", &str);
                 ~~~~^
palindrome.cpp:117:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < vec[i].size(); j++)
                         ~~^~~~~~~~~~~~~~~
palindrome.cpp:75:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s", &str);
     ~~~~~^~~~~~~~~~~~

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 7568 KB Output is correct
2 Correct 10 ms 7568 KB Output is correct
3 Correct 11 ms 7568 KB Output is correct
4 Correct 10 ms 7568 KB Output is correct
5 Correct 12 ms 7624 KB Output is correct
6 Correct 11 ms 7624 KB Output is correct
7 Correct 10 ms 7628 KB Output is correct
8 Correct 10 ms 7660 KB Output is correct
9 Correct 10 ms 7744 KB Output is correct
10 Correct 12 ms 7744 KB Output is correct
11 Correct 9 ms 7744 KB Output is correct
12 Correct 11 ms 7744 KB Output is correct
13 Correct 13 ms 7744 KB Output is correct
14 Correct 11 ms 7744 KB Output is correct
15 Correct 11 ms 7744 KB Output is correct
16 Correct 11 ms 7744 KB Output is correct
17 Correct 12 ms 7744 KB Output is correct
18 Correct 9 ms 7744 KB Output is correct
19 Correct 10 ms 7744 KB Output is correct
20 Correct 11 ms 7744 KB Output is correct
21 Correct 11 ms 7744 KB Output is correct
22 Correct 11 ms 7744 KB Output is correct
23 Correct 11 ms 7744 KB Output is correct
24 Correct 11 ms 7744 KB Output is correct
25 Correct 12 ms 7744 KB Output is correct
26 Correct 11 ms 7744 KB Output is correct
27 Correct 12 ms 7744 KB Output is correct
28 Correct 12 ms 7744 KB Output is correct
29 Correct 10 ms 7744 KB Output is correct
30 Correct 12 ms 7744 KB Output is correct
31 Correct 10 ms 7744 KB Output is correct
32 Correct 9 ms 7744 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 7788 KB Output is correct
2 Correct 13 ms 7916 KB Output is correct
3 Correct 11 ms 7916 KB Output is correct
4 Correct 13 ms 7916 KB Output is correct
5 Correct 11 ms 7916 KB Output is correct
6 Correct 11 ms 7916 KB Output is correct
7 Correct 15 ms 7916 KB Output is correct
8 Correct 13 ms 7916 KB Output is correct
9 Correct 14 ms 7916 KB Output is correct
10 Correct 13 ms 7916 KB Output is correct
11 Correct 12 ms 7916 KB Output is correct
12 Correct 13 ms 7916 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 47 ms 9324 KB Output is correct
2 Correct 49 ms 9324 KB Output is correct
3 Correct 45 ms 9452 KB Output is correct
4 Correct 64 ms 9452 KB Output is correct
5 Correct 58 ms 9452 KB Output is correct
6 Correct 52 ms 9452 KB Output is correct
7 Correct 52 ms 9452 KB Output is correct
8 Correct 54 ms 9452 KB Output is correct
9 Correct 43 ms 9452 KB Output is correct
10 Correct 55 ms 9452 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 558 ms 23812 KB Output is correct
2 Correct 565 ms 23812 KB Output is correct
3 Correct 456 ms 24540 KB Output is correct
4 Correct 906 ms 24540 KB Output is correct
5 Correct 717 ms 24540 KB Output is correct
6 Correct 694 ms 24540 KB Output is correct
7 Correct 710 ms 24540 KB Output is correct
8 Correct 635 ms 24540 KB Output is correct
9 Correct 648 ms 24540 KB Output is correct
10 Correct 744 ms 24540 KB Output is correct

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1085 ms 24540 KB Time limit exceeded
2 Halted 0 ms 0 KB -