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Submission #977476

# Submission time Handle Problem Language Result Execution time Memory
977476 2024-05-08T03:47:39 Z vjudge1 Lampice (COCI19_lampice) C++17
110 / 110
 4287 ms 28732 KB 
#include<bits/stdc++.h>
using namespace std;
unordered_map<int,int> mp[25010];
#define N 50010
#define int long long
int palin[N],vis[N],pw[N],hsh[N],sz[N],val[N],ans,rt,B=31,mod=1e9+7;
vector<int>adj[N],V{0};
void dfssz(int n,int p,int tot){
    palin[n]=0;
    int mx=0;
    sz[n]=1;
    for(auto i:adj[n])
        if(i-p&&!vis[i]) {
            dfssz(i,n,tot),
            sz[n]+=sz[i],
            mx=max(mx,sz[i]);
        }
    if(sz[n]*2>=tot&&mx*2<=tot)
        rt=n;
}
void dfshash(int n,int p){
    hsh[n]=(hsh[p]*B+val[n])%mod;
    for(auto i:adj[n])
        if(!vis[i]&&i-p)
            dfshash(i,n);
}
int MD;
void calcdfs(int n,int p,int l,int d,int h){
    MD=max(MD,d);
    if(d>l||ans) return;
    ans|=mp[d][(hsh[n]-val[V[1]]*pw[d]%mod+mod)%mod];
    h=(h+pw[d]*val[n])%mod;
    palin[n]=hsh[n]==h;
    for(auto i:adj[n])
        if(!vis[i]&&i-p)
            calcdfs(i,n,l,d+1,h);
}
void upddfs(int n,int p,int l,int d){
    if(ans||d>l) return;
    V.push_back(n);
    int c;
    if(d+l/2>=l&&palin[c=V[2*d-l]])
        mp[l-d][(hsh[n]-hsh[c]*pw[l-d]%mod+mod)%mod]=1;
    for(auto i:adj[n])
        if(i-p&&!vis[i])
            upddfs(i,n,l,d+1);
    V.pop_back();
}
void cent(int n,int s,int l){
    if(ans)
        return;
    MD=0;
    dfssz(n,0,s);
    dfssz(n=rt,0,s);
    palin[n]=1;
    dfshash(n,0);
    vis[n]=1;
    V.push_back(n);
    for(auto i:adj[n]) if(!vis[i])
        calcdfs(i,n,l,1,val[n]),
        upddfs(i,n,l,2);
    if(mp[0][0])
        ans=1;
    for(int i=0;i<=min(l/2,MD);i++)
        mp[i].clear();
    reverse(adj[n].begin(),adj[n].end());
    for(auto i:adj[n]) if(!vis[i])
        calcdfs(i,n,l,1,val[n]),
        upddfs(i,n,l,2);
    if(mp[0][0])
        ans=1;
    for(int i=0;i<=min(l/2,MD);i++)
        mp[i].clear();
    V.pop_back();
    for(auto i:adj[n])
        if(!vis[i])
            cent(i,sz[i],l);
}
signed main() {
    pw[0]=1;
    for(int i=1;i<N;i++)
        pw[i]=pw[i-1]*B%mod;
    cin.tie(0)->sync_with_stdio(0);
    int n;
    string str;
    cin>>n>>str;
    for(int i=1;i<=n;i++)
        val[i]=str[i-1]-'`';
    if(n==1)
        return puts("1"),0;
    for(int i=1;i<n;i++){
        int a,b;
        cin>>a>>b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    int l=0,r=n/2;
    while(l<r){
        int mid=l+r+1>>1;
        for(int i=1;i<=n;i++)
            palin[i]=vis[i]=ans=0;
        cent(1,n,mid*2+1);
        if(ans)
            l=mid;
        else r=mid-1;
    }
    int l1=l,r1=n/2;
    while(l1<r1){
        int mid=l1+r1+1>>1;
        for(int i=1;i<=n;i++)
            palin[i]=vis[i]=ans=0;
        cent(1,n,mid*2);
        if(ans)
            l1=mid;
        else r1=mid-1;
    }
    cout<<max(l1*2,l*2+1)<<'\n';
}

Compilation message

lampice.cpp: In function 'int main()':
lampice.cpp:99:20: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   99 |         int mid=l+r+1>>1;
      |                 ~~~^~
lampice.cpp:109:22: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  109 |         int mid=l1+r1+1>>1;
      |                 ~~~~~^~

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 5212 KB Output is correct
2 Correct 10 ms 5300 KB Output is correct
3 Correct 42 ms 5760 KB Output is correct
4 Correct 41 ms 5468 KB Output is correct
5 Correct 2 ms 5212 KB Output is correct
6 Correct 2 ms 5212 KB Output is correct
7 Correct 1 ms 5212 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 2080 ms 28732 KB Output is correct
2 Correct 1734 ms 14800 KB Output is correct
3 Correct 1024 ms 14796 KB Output is correct
4 Correct 1119 ms 15192 KB Output is correct
5 Correct 1791 ms 18668 KB Output is correct
6 Correct 164 ms 14672 KB Output is correct

Subtask #3
31.0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 4287 ms 26964 KB Output is correct
2 Correct 3035 ms 11632 KB Output is correct
3 Correct 3461 ms 12228 KB Output is correct
4 Correct 3215 ms 10168 KB Output is correct
5 Correct 2907 ms 9580 KB Output is correct
6 Correct 2733 ms 11640 KB Output is correct

Subtask #4
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 5212 KB Output is correct
2 Correct 10 ms 5300 KB Output is correct
3 Correct 42 ms 5760 KB Output is correct
4 Correct 41 ms 5468 KB Output is correct
5 Correct 2 ms 5212 KB Output is correct
6 Correct 2 ms 5212 KB Output is correct
7 Correct 1 ms 5212 KB Output is correct
8 Correct 2080 ms 28732 KB Output is correct
9 Correct 1734 ms 14800 KB Output is correct
10 Correct 1024 ms 14796 KB Output is correct
11 Correct 1119 ms 15192 KB Output is correct
12 Correct 1791 ms 18668 KB Output is correct
13 Correct 164 ms 14672 KB Output is correct
14 Correct 4287 ms 26964 KB Output is correct
15 Correct 3035 ms 11632 KB Output is correct
16 Correct 3461 ms 12228 KB Output is correct
17 Correct 3215 ms 10168 KB Output is correct
18 Correct 2907 ms 9580 KB Output is correct
19 Correct 2733 ms 11640 KB Output is correct
20 Correct 1838 ms 8016 KB Output is correct
21 Correct 2122 ms 9612 KB Output is correct
22 Correct 3328 ms 9204 KB Output is correct
23 Correct 645 ms 7764 KB Output is correct
24 Correct 2497 ms 9668 KB Output is correct
25 Correct 3262 ms 8536 KB Output is correct
26 Correct 4069 ms 11408 KB Output is correct
27 Correct 4125 ms 20036 KB Output is correct
28 Correct 2645 ms 7428 KB Output is correct
29 Correct 2534 ms 7472 KB Output is correct
30 Correct 3202 ms 10144 KB Output is correct
31 Correct 2969 ms 8452 KB Output is correct
32 Correct 2584 ms 11464 KB Output is correct
33 Correct 1539 ms 8888 KB Output is correct