oj.uz

Submission #202842

# Submission time Handle Problem Language Result Execution time Memory
202842 2020-02-18T07:48:01 Z rdd6584 Lampice (COCI19_lampice) C++14
110 / 110
 4160 ms 56744 KB 
#include <bits/stdc++.h>
#define sz(x) (int)(x).size()
#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3")
#pragma GCC optimization ("unroll-loops")
using namespace std;

typedef long long ll;

int n;
const int B = 100007;
const ll pr[2] = { 1000000009, 1000000021 };
ll rhq[50001][2];
int dh[17][50001][2];
int rh[17][50001][2];
int pal[17][50001];
vector<int> v[50001];

unordered_map<ll, int> um[50001];
int rotn[50001];
char visit[50001];
char s[50001];
int ha, hb;

vector<int> road;
int len, flag, ans = 1;

void preHash(int o, int pa, int di, int &dep) {
    dh[dep][o][0] = (dh[dep][pa][0] + rhq[di][0] * s[o]) % pr[0];
    dh[dep][o][1] = (dh[dep][pa][1] + rhq[di][1] * s[o]) % pr[1];

    rh[dep][o][0] = (rh[dep][pa][0] + rhq[n - di][0] * s[o]) % pr[0];
    rh[dep][o][1] = (rh[dep][pa][1] + rhq[n - di][1] * s[o]) % pr[1];

    if (rh[dep][o][0] == dh[dep][o][0] * rhq[n - di][0] % pr[0] &&
        rh[dep][o][1] == dh[dep][o][1] * rhq[n - di][1] % pr[1])
        pal[dep][o] = 1;

    if (di < len) {
        for (int &i : v[o])
            if (i != pa && !visit[i])
                preHash(i, o, di + 1, dep);
    }
}

int pre(int o, int pa) {
    int ret = 1;
    for (int &i : v[o])
        if (i != pa && !visit[i])
            ret += pre(i, o);
    return rotn[o] = ret;
}

int cent(int o, int pa, int cap) {
    for (int &i : v[o])
        if (i != pa && !visit[i] && rotn[i] > cap)
            return cent(i, o, cap);
    return o;
}

void pl(int o, int pa, int di, int h1, int h2, int fl, int &root) {
    h1 = (h1 + rhq[di][0] * s[o]) % pr[0];
    h2 = (h2 + rhq[di][1] * s[o]) % pr[1];
    ha = h1 * rhq[n - di][0] % pr[0];
    hb = h2 * rhq[n - di][1] % pr[1];
    um[root][ha * pr[1] + hb] += fl;

    if (di < len) {
        for (int &i : v[o])
            if (i != pa && !visit[i])
                pl(i, o, di + 1, h1, h2, fl, root);
    }
}

void cal(int o, int pa, int di, int &dep, int &root) {
    road.push_back(o);
    int p = 2 * di + 1 - len;

    if (sz(road) > p && p >= 0 && pal[dep][road[p]]) {
        ha = (dh[dep][o][0] - dh[dep][road[p]][0] + pr[0]) * rhq[n - di][0] % pr[0];
        hb = (dh[dep][o][1] - dh[dep][road[p]][1] + pr[1]) * rhq[n - di][1] % pr[1];

        if (um[root].find(ha * pr[1] + hb) != um[root].end() && um[root][ha * pr[1] + hb] >= 1)
            flag = 1;
    }

    if (di < len && !flag)
        for (int &i : v[o])
            if (i != pa && !visit[i])
                cal(i, o, di + 1, dep, root);

    road.pop_back();
}

void gopre(int o, int dep) {
    pre(o, o);
    int t = cent(o, o, rotn[o] / 2);
    visit[t]++;
    um[t][0] = 100000;
    preHash(t, t, 0, dep);

    for (int &i : v[t])
        if (!visit[i])
            pl(i, t, 1, 0, 0, 1, t);

    for (int &i : v[t])
        if (!visit[i] && !flag)
            gopre(i, dep + 1);

    visit[t]--;
}


void go(int o, int dep) {
    pre(o, o);
    int t = cent(o, o, rotn[o] / 2);
    visit[t]++;

    road.push_back(t);
    for (int &i : v[t])
        if (!visit[i] && !flag) {
            pl(i, t, 1, 0, 0, -1, t);
            cal(i, t, 1, dep, t);
            pl(i, t, 1, 0, 0, 1, t);
        }
    road.pop_back();

    for (int &i : v[t])
        if (!visit[i] && !flag)
            go(i, dep + 1);

    visit[t]--;
}

int main() {
    scanf("%d", &n);
    scanf("%s", s);

    rhq[0][0] = rhq[0][1] = 1;
    for (int i = 1; i <= n; i++) {
        rhq[i][0] = rhq[i - 1][0] * B % pr[0];
        rhq[i][1] = rhq[i - 1][1] * B % pr[1];
    }

    for (int i = 0; i < n - 1; i++) {
        int a, b;
        scanf("%d %d", &a, &b);
        a--; b--;
        v[a].push_back(b);
        v[b].push_back(a);
    }

    len = n;
    gopre(0, 0);

    int l = 1, r = (n - 1) / 2, mid;
    while (l <= r) {
        mid = (l + r) / 2;
        flag = 0;
        len = mid * 2 + 1;
        go(0, 0);
        if (flag) l = mid + 1;
        else r = mid - 1;
    }
    ans = max(ans, r * 2 + 1);

    l = ans / 2 + 1, r = n / 2;
    while (l <= r) {
        mid = (l + r) / 2;
        flag = 0;
        len = mid * 2;
        go(0, 0);
        if (flag) l = mid + 1;
        else r = mid - 1;
    }
    ans = max(ans, r * 2);
    printf("%d", ans);
}

Compilation message

lampice.cpp:5:0: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
 #pragma GCC optimization ("unroll-loops")
 
lampice.cpp: In function 'int main()':
lampice.cpp:136:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
lampice.cpp:137:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s", s);
     ~~~~~^~~~~~~~~
lampice.cpp:147:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 4472 KB Output is correct
2 Correct 15 ms 4728 KB Output is correct
3 Correct 39 ms 5244 KB Output is correct
4 Correct 58 ms 5496 KB Output is correct
5 Correct 7 ms 4216 KB Output is correct
6 Correct 7 ms 4216 KB Output is correct
7 Correct 7 ms 4216 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1702 ms 49232 KB Output is correct
2 Correct 2044 ms 50600 KB Output is correct
3 Correct 1267 ms 51880 KB Output is correct
4 Correct 1367 ms 54156 KB Output is correct
5 Correct 2206 ms 56744 KB Output is correct
6 Correct 254 ms 43512 KB Output is correct

Subtask #3
31.0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 3579 ms 50440 KB Output is correct
2 Correct 4152 ms 48552 KB Output is correct
3 Correct 4145 ms 49044 KB Output is correct
4 Correct 4160 ms 39860 KB Output is correct
5 Correct 3473 ms 44456 KB Output is correct
6 Correct 3135 ms 40360 KB Output is correct

Subtask #4
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 4472 KB Output is correct
2 Correct 15 ms 4728 KB Output is correct
3 Correct 39 ms 5244 KB Output is correct
4 Correct 58 ms 5496 KB Output is correct
5 Correct 7 ms 4216 KB Output is correct
6 Correct 7 ms 4216 KB Output is correct
7 Correct 7 ms 4216 KB Output is correct
8 Correct 1702 ms 49232 KB Output is correct
9 Correct 2044 ms 50600 KB Output is correct
10 Correct 1267 ms 51880 KB Output is correct
11 Correct 1367 ms 54156 KB Output is correct
12 Correct 2206 ms 56744 KB Output is correct
13 Correct 254 ms 43512 KB Output is correct
14 Correct 3579 ms 50440 KB Output is correct
15 Correct 4152 ms 48552 KB Output is correct
16 Correct 4145 ms 49044 KB Output is correct
17 Correct 4160 ms 39860 KB Output is correct
18 Correct 3473 ms 44456 KB Output is correct
19 Correct 3135 ms 40360 KB Output is correct
20 Correct 2004 ms 28328 KB Output is correct
21 Correct 2207 ms 33064 KB Output is correct
22 Correct 3496 ms 42152 KB Output is correct
23 Correct 869 ms 17400 KB Output is correct
24 Correct 2805 ms 36856 KB Output is correct
25 Correct 3353 ms 35040 KB Output is correct
26 Correct 4032 ms 46072 KB Output is correct
27 Correct 3644 ms 44584 KB Output is correct
28 Correct 3157 ms 28024 KB Output is correct
29 Correct 3060 ms 28280 KB Output is correct
30 Correct 3860 ms 33896 KB Output is correct
31 Correct 3395 ms 30456 KB Output is correct
32 Correct 2928 ms 41896 KB Output is correct
33 Correct 1790 ms 30440 KB Output is correct