oj.uz

Submission #1005556

# Submission time Handle Problem Language Result Execution time Memory
1005556 2024-06-22T15:35:34 Z anango Necklace (Subtask 1-3) (BOI19_necklace1) C++17
9 / 85
 552 ms 736 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
5.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 233 ms 344 KB Output is correct
2 Partially correct 121 ms 348 KB Output is partially correct
3 Correct 429 ms 348 KB Output is correct
4 Correct 212 ms 344 KB Output is correct
5 Correct 42 ms 348 KB Output is correct

Subtask #2
4.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 233 ms 344 KB Output is correct
2 Partially correct 121 ms 348 KB Output is partially correct
3 Correct 429 ms 348 KB Output is correct
4 Correct 212 ms 344 KB Output is correct
5 Correct 42 ms 348 KB Output is correct
6 Partially correct 244 ms 348 KB Output is partially correct
7 Correct 129 ms 596 KB Output is correct
8 Partially correct 538 ms 600 KB Output is partially correct
9 Correct 209 ms 348 KB Output is correct
10 Correct 11 ms 348 KB Output is correct
11 Correct 13 ms 348 KB Output is correct
12 Correct 445 ms 436 KB Output is correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 233 ms 344 KB Output is correct
2 Partially correct 121 ms 348 KB Output is partially correct
3 Correct 429 ms 348 KB Output is correct
4 Correct 212 ms 344 KB Output is correct
5 Correct 42 ms 348 KB Output is correct
6 Partially correct 244 ms 348 KB Output is partially correct
7 Correct 129 ms 596 KB Output is correct
8 Partially correct 538 ms 600 KB Output is partially correct
9 Correct 209 ms 348 KB Output is correct
10 Correct 11 ms 348 KB Output is correct
11 Correct 13 ms 348 KB Output is correct
12 Correct 445 ms 436 KB Output is correct
13 Partially correct 286 ms 348 KB Output is partially correct
14 Correct 135 ms 596 KB Output is correct
15 Partially correct 552 ms 488 KB Output is partially correct
16 Partially correct 295 ms 736 KB Output is partially correct
17 Incorrect 3 ms 348 KB Output isn't correct
18 Halted 0 ms 0 KB -