oj.uz

답안 #71849

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
71849 2018-08-25T17:03:16 Z evpipis 회문 (APIO14_palindrome) C++11
65 / 100
 1000 ms 60248 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;
}

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;
}

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]] || (suf[i]+k<n?ran[suf[i]+k]:0) != (suf[i-1]+k<n?ran[suf[i-1]+k]:0))
                tmp[suf[i]] = ++ptr;
            else
                tmp[suf[i]] = ptr;
        }

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

    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:90:21: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[300005]' [-Wformat=]
     scanf("%s", &str);
                 ~~~~^
palindrome.cpp:150:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < vec[i].size(); j++)
                         ~~^~~~~~~~~~~~~~~
palindrome.cpp:90:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s", &str);
     ~~~~~^~~~~~~~~~~~

Subtask #1
0 / 8.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 7416 KB Output is correct
2 Correct 9 ms 7416 KB Output is correct
3 Correct 8 ms 7436 KB Output is correct
4 Correct 9 ms 7448 KB Output is correct
5 Correct 8 ms 7632 KB Output is correct
6 Correct 8 ms 7632 KB Output is correct
7 Correct 8 ms 7632 KB Output is correct
8 Correct 9 ms 7632 KB Output is correct
9 Correct 9 ms 7632 KB Output is correct
10 Incorrect 10 ms 7632 KB Output isn't correct
11 Halted 0 ms 0 KB -

Subtask #2
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 7712 KB Output is correct
2 Correct 9 ms 7840 KB Output is correct
3 Correct 10 ms 7840 KB Output is correct
4 Correct 10 ms 7840 KB Output is correct
5 Correct 11 ms 7840 KB Output is correct
6 Correct 10 ms 7856 KB Output is correct
7 Correct 10 ms 7868 KB Output is correct
8 Correct 9 ms 7868 KB Output is correct
9 Correct 12 ms 7868 KB Output is correct
10 Correct 11 ms 7868 KB Output is correct
11 Correct 10 ms 7868 KB Output is correct
12 Correct 10 ms 7868 KB Output is correct

Subtask #3
24.0 / 24.0

# 결과 실행 시간 메모리 Grader output
1 Correct 24 ms 9452 KB Output is correct
2 Correct 27 ms 9452 KB Output is correct
3 Correct 25 ms 9452 KB Output is correct
4 Correct 26 ms 9604 KB Output is correct
5 Correct 24 ms 9604 KB Output is correct
6 Correct 24 ms 9604 KB Output is correct
7 Correct 21 ms 9604 KB Output is correct
8 Correct 27 ms 9604 KB Output is correct
9 Correct 27 ms 9604 KB Output is correct
10 Correct 25 ms 9604 KB Output is correct

Subtask #4
26.0 / 26.0

# 결과 실행 시간 메모리 Grader output
1 Correct 226 ms 24988 KB Output is correct
2 Correct 199 ms 24988 KB Output is correct
3 Correct 222 ms 25060 KB Output is correct
4 Correct 209 ms 25284 KB Output is correct
5 Correct 228 ms 25284 KB Output is correct
6 Correct 226 ms 25284 KB Output is correct
7 Correct 209 ms 25284 KB Output is correct
8 Correct 281 ms 25284 KB Output is correct
9 Correct 262 ms 25284 KB Output is correct
10 Correct 246 ms 25284 KB Output is correct

Subtask #5
0 / 27.0

# 결과 실행 시간 메모리 Grader output
1 Correct 747 ms 59180 KB Output is correct
2 Correct 714 ms 59180 KB Output is correct
3 Correct 642 ms 60248 KB Output is correct
4 Correct 702 ms 60248 KB Output is correct
5 Correct 810 ms 60248 KB Output is correct
6 Correct 682 ms 60248 KB Output is correct
7 Correct 711 ms 60248 KB Output is correct
8 Execution timed out 1073 ms 60248 KB Time limit exceeded
9 Halted 0 ms 0 KB -