oj.uz

Submission #1005557

# Submission time Handle Problem Language Result Execution time Memory
1005557 2024-06-22T15:35:51 Z anango Necklace (Subtask 1-3) (BOI19_necklace1) C++17
45 / 85
 777 ms 592 KB 
#include <bits/stdc++.h>
#define int long long

using namespace std;
mt19937 rng;
int INF = 1LL<<60;
int p = 2071723;
int MOD = 1000000033;

string a;
string b;
int n,m;

vector<int> hashes;

void compute_hash(string s) {
    int n1 = s.size();
    hashes.clear();
    hashes=vector<int>(n1+1,0);
    int ha = 0;
    for (int i=0; i<n1; i++) {
        ha += s[i]-'a';
        ha *= p;
        ha %= MOD;
        hashes[i+1] = ha;
    }
    
}

int exp(int p, int n) {
    int ans=1;
    int r = p;
    for (int i=0; i<30; i++) {
        if (n&(1<<i)) {
            ans*=r;
            ans%=MOD;
        }
        r*=r;
        r%=MOD;
    }
    return ans;
}

int gethash(int l, int r) {
    int h1 = hashes[l];
    int h2 = hashes[r+1];
    h1 *= exp(p,r-l+1);
    h1%=MOD;
    int dif = h2-h1;
    dif%=MOD;
    dif+=MOD;
    dif%=MOD;
    return dif;
}

bool check(int a, int b, int length) {
    return gethash(a,a+length-1)==gethash(b,b+length-1);
}
bool verify(int i, int j, int length) {
    //checks if i...i+length-1 in a = j...j+length-1 in b
    return gethash(i,length-1)==gethash(n+j, length-1);
}

vector<pair<int,int>> solve() {
    compute_hash(a+b);
    int ans = 0;
    pair<int,int> xpos;
    pair<int,int> ypos;
    for (int trial=0; trial*ans<3000000; trial++) {
        int i,j;
        i=rng()%n;  
        j=rng()%m;
        if (a[i]!=b[j]) {
            continue;
        }
        int l,r;
        l=0;
        r=0;
        while (l+i>=0 && l+j>=0 && a[i+l]==b[j+l]) {
            //cout << "doing " << i <<" " << l <<" " << a[i+l] <<" " << b[j+l] << endl;
            l--;
        }
        l++;
        while (r+i<=n-1 && r+j<=m-1 && a[i+r]==b[j+r]) {
            r++;
        }
        r--;
        int length = r-l+1;
        int subans = length;
        if (subans>ans) {
            ans=subans;
            xpos={i+l,i+l+length};
            ypos={j+l,j+l+length};
        }
        for (int blubber=1; blubber<=length; blubber++) { //add it on both sides
            int la = i+r+1;
            int ra = i+r+blubber;
            int lb = j+l-blubber;
            int rb = j+l-1;
            if (!(0<=la && la<=n-1) || !(0<=lb && rb<=m-1)) {
                break;
            }
            if (gethash(la,ra)==gethash(n+lb,n+rb)) {
                int subans = blubber+length;
                if (subans>ans) {
                    //cout << a <<" " << b <<" " << ans <<" " << i <<" " << j <<" " << blubber <<" " << subans << endl;
                    //cout << la <<" " << ra <<" " << lb <<" " << rb << endl;
                    ans=subans;
                    xpos = {i+l,ra};
                    ypos = {lb,j+r};
                }
            }
        }

    }
    return {{ans,ans},xpos,ypos};

    
}

signed main() {
    //freopen("input.txt","r", stdin);
    //freopen("output.txt","w",stdout);
    cin >> a;
    cin >> b;
    n=a.size();
    m=b.size();
    vector<pair<int,int>> ans2;
    vector<int> ans(3);
    ans2=solve();
    ans[0] = ans2[0].first;
    ans[1] = ans2[1].first;
    ans[2] = ans2[2].first;
    reverse(b.begin(), b.end());
    ans2 = solve();
    if (ans2[0].first>ans[0]) {
        ans[0] = ans2[0].first;
        ans[1] = ans2[1].first;
        ans[2] = m-ans2[2].second-1;
    }
    reverse(a.begin(), a.end());
    ans2 = solve();
    if (ans2[0].first>ans[0]) {
        ans[0] = ans2[0].first;
        ans[1] = n-ans2[1].second-1;
        ans[2] = m-ans2[2].second-1;
    }
    reverse(b.begin(), b.end());
    ans2 = solve();
    if (ans2[0].first>ans[0]) {
        ans[0] = ans2[0].first;
        ans[1] = n-ans2[1].second-1;
        ans[2] = ans2[2].first;
    }
    cout << ans[0] << endl;
    cout << ans[1] <<" " << ans[2] << endl;


    //want to store for each x and j, the smallest t such that match[x][t]+t = j
    

}

Subtask #1
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 323 ms 348 KB Output is correct
2 Correct 176 ms 412 KB Output is correct
3 Correct 597 ms 348 KB Output is correct
4 Correct 304 ms 344 KB Output is correct
5 Correct 62 ms 344 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 323 ms 348 KB Output is correct
2 Correct 176 ms 412 KB Output is correct
3 Correct 597 ms 348 KB Output is correct
4 Correct 304 ms 344 KB Output is correct
5 Correct 62 ms 344 KB Output is correct
6 Correct 353 ms 428 KB Output is correct
7 Correct 196 ms 444 KB Output is correct
8 Correct 593 ms 436 KB Output is correct
9 Correct 320 ms 344 KB Output is correct
10 Correct 15 ms 348 KB Output is correct
11 Correct 19 ms 348 KB Output is correct
12 Correct 589 ms 420 KB Output is correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 323 ms 348 KB Output is correct
2 Correct 176 ms 412 KB Output is correct
3 Correct 597 ms 348 KB Output is correct
4 Correct 304 ms 344 KB Output is correct
5 Correct 62 ms 344 KB Output is correct
6 Correct 353 ms 428 KB Output is correct
7 Correct 196 ms 444 KB Output is correct
8 Correct 593 ms 436 KB Output is correct
9 Correct 320 ms 344 KB Output is correct
10 Correct 15 ms 348 KB Output is correct
11 Correct 19 ms 348 KB Output is correct
12 Correct 589 ms 420 KB Output is correct
13 Partially correct 378 ms 344 KB Output is partially correct
14 Correct 190 ms 348 KB Output is correct
15 Partially correct 777 ms 592 KB Output is partially correct
16 Partially correct 365 ms 344 KB Output is partially correct
17 Incorrect 3 ms 348 KB Output isn't correct
18 Halted 0 ms 0 KB -