oj.uz

Submission #71858

# Submission time Handle Problem Language Result Execution time Memory
71858 2018-08-25T17:24:16 Z evpipis Palindromes (APIO14_palindrome) C++11
73 / 100
 1000 ms 61540 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];
int tmp[len], ran[len], cnt[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;
}

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;
}

void radix(int k){
    for (int i = 0; i <= max(n, 300); i++)
        cnt[i] = 0;
    for (int i = 0; i < n; i++)
        cnt[(suf[i]+k<n?ran[suf[i]+k]:0)+1]++;
    for (int i = 1; i <= max(n, 300); i++)
        cnt[i] += cnt[i-1];

    for (int i = 0; i < n; i++)
        tmp[cnt[(suf[i]+k<n?ran[suf[i]+k]:0)]++] = suf[i];
    for (int i = 0; i < n; i++)
        suf[i] = tmp[i];
}

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); // suffix array before :(

    for (int i = 0; i < n; i++)
        ran[i] = str[i];
    for (int k = 1; k <= n; k*=2){
        radix(k);
        radix(0);

        int ptr = -1;
        for (int i = 0; i < n; i++){
            if (i == 0 || ran[suf[i]] != ran[suf[i-1]] || ran[suf[i]+k] != ran[suf[i-1]+k])
                tmp[suf[i]] = ++ptr;
            else
                tmp[suf[i]] = ptr;
        }

        for (int i = 0; i < n; i++)
            ran[i] = tmp[i];

        if (ptr == n-1) break;
    }

    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:85:21: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[300005]' [-Wformat=]
     scanf("%s", &str);
                 ~~~~^
palindrome.cpp:147:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < vec[i].size(); j++)
                         ~~^~~~~~~~~~~~~~~
palindrome.cpp:85:10: 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 9 ms 7416 KB Output is correct
2 Correct 9 ms 7564 KB Output is correct
3 Correct 10 ms 7564 KB Output is correct
4 Correct 8 ms 7564 KB Output is correct
5 Correct 8 ms 7656 KB Output is correct
6 Correct 11 ms 7656 KB Output is correct
7 Correct 9 ms 7656 KB Output is correct
8 Correct 9 ms 7720 KB Output is correct
9 Correct 9 ms 7720 KB Output is correct
10 Correct 9 ms 7752 KB Output is correct
11 Correct 10 ms 7752 KB Output is correct
12 Correct 9 ms 7764 KB Output is correct
13 Correct 8 ms 7764 KB Output is correct
14 Correct 8 ms 7764 KB Output is correct
15 Correct 9 ms 7764 KB Output is correct
16 Correct 8 ms 7764 KB Output is correct
17 Correct 9 ms 7764 KB Output is correct
18 Correct 9 ms 7764 KB Output is correct
19 Correct 8 ms 7764 KB Output is correct
20 Correct 9 ms 7788 KB Output is correct
21 Correct 10 ms 7788 KB Output is correct
22 Correct 8 ms 7788 KB Output is correct
23 Correct 10 ms 7788 KB Output is correct
24 Correct 9 ms 7788 KB Output is correct
25 Correct 10 ms 7788 KB Output is correct
26 Correct 9 ms 7788 KB Output is correct
27 Correct 8 ms 7788 KB Output is correct
28 Correct 9 ms 7788 KB Output is correct
29 Correct 9 ms 7788 KB Output is correct
30 Correct 10 ms 7788 KB Output is correct
31 Correct 9 ms 7788 KB Output is correct
32 Correct 8 ms 7788 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 7788 KB Output is correct
2 Correct 10 ms 7788 KB Output is correct
3 Correct 9 ms 7788 KB Output is correct
4 Correct 9 ms 7792 KB Output is correct
5 Correct 11 ms 7792 KB Output is correct
6 Correct 8 ms 7792 KB Output is correct
7 Correct 9 ms 7792 KB Output is correct
8 Correct 11 ms 7792 KB Output is correct
9 Correct 10 ms 7792 KB Output is correct
10 Correct 10 ms 7884 KB Output is correct
11 Correct 9 ms 7884 KB Output is correct
12 Correct 10 ms 7884 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 9452 KB Output is correct
2 Correct 27 ms 9452 KB Output is correct
3 Correct 22 ms 9580 KB Output is correct
4 Correct 22 ms 9580 KB Output is correct
5 Correct 21 ms 9580 KB Output is correct
6 Correct 22 ms 9580 KB Output is correct
7 Correct 22 ms 9580 KB Output is correct
8 Correct 23 ms 9580 KB Output is correct
9 Correct 19 ms 9580 KB Output is correct
10 Correct 21 ms 9580 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 195 ms 25120 KB Output is correct
2 Correct 211 ms 25120 KB Output is correct
3 Correct 195 ms 25584 KB Output is correct
4 Correct 202 ms 25584 KB Output is correct
5 Correct 193 ms 25584 KB Output is correct
6 Correct 182 ms 25584 KB Output is correct
7 Correct 223 ms 25584 KB Output is correct
8 Correct 180 ms 25584 KB Output is correct
9 Correct 245 ms 25584 KB Output is correct
10 Correct 202 ms 25584 KB Output is correct

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 723 ms 59148 KB Output is correct
2 Correct 643 ms 59148 KB Output is correct
3 Correct 641 ms 61540 KB Output is correct
4 Correct 707 ms 61540 KB Output is correct
5 Correct 677 ms 61540 KB Output is correct
6 Correct 729 ms 61540 KB Output is correct
7 Correct 705 ms 61540 KB Output is correct
8 Correct 631 ms 61540 KB Output is correct
9 Correct 663 ms 61540 KB Output is correct
10 Correct 769 ms 61540 KB Output is correct
11 Correct 698 ms 61540 KB Output is correct
12 Execution timed out 1022 ms 61540 KB Time limit exceeded