oj.uz

Submission #1005554

# Submission time Handle Problem Language Result Execution time Memory
1005554 2024-06-22T15:34:42 Z anango Necklace (Subtask 1-3) (BOI19_necklace1) C++17
9 / 85
 713 ms 600 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*2; 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
5.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 201 ms 348 KB Output is correct
2 Partially correct 93 ms 348 KB Output is partially correct
3 Correct 495 ms 344 KB Output is correct
4 Correct 266 ms 344 KB Output is correct
5 Correct 43 ms 348 KB Output is correct

Subtask #2
4.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 201 ms 348 KB Output is correct
2 Partially correct 93 ms 348 KB Output is partially correct
3 Correct 495 ms 344 KB Output is correct
4 Correct 266 ms 344 KB Output is correct
5 Correct 43 ms 348 KB Output is correct
6 Partially correct 184 ms 344 KB Output is partially correct
7 Correct 97 ms 344 KB Output is correct
8 Partially correct 522 ms 344 KB Output is partially correct
9 Correct 288 ms 344 KB Output is correct
10 Correct 10 ms 344 KB Output is correct
11 Correct 14 ms 348 KB Output is correct
12 Correct 515 ms 428 KB Output is correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 201 ms 348 KB Output is correct
2 Partially correct 93 ms 348 KB Output is partially correct
3 Correct 495 ms 344 KB Output is correct
4 Correct 266 ms 344 KB Output is correct
5 Correct 43 ms 348 KB Output is correct
6 Partially correct 184 ms 344 KB Output is partially correct
7 Correct 97 ms 344 KB Output is correct
8 Partially correct 522 ms 344 KB Output is partially correct
9 Correct 288 ms 344 KB Output is correct
10 Correct 10 ms 344 KB Output is correct
11 Correct 14 ms 348 KB Output is correct
12 Correct 515 ms 428 KB Output is correct
13 Partially correct 201 ms 600 KB Output is partially correct
14 Correct 101 ms 496 KB Output is correct
15 Partially correct 713 ms 348 KB Output is partially correct
16 Partially correct 335 ms 528 KB Output is partially correct
17 Incorrect 3 ms 348 KB Output isn't correct
18 Halted 0 ms 0 KB -