oj.uz

Submission #1005551

# Submission time Handle Problem Language Result Execution time Memory
1005551 2024-06-22T15:31:36 Z anango Necklace (Subtask 1-3) (BOI19_necklace1) C++17
45 / 85
 910 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<2000000; 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<=2*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)) {
                continue;
            }
            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 256 ms 416 KB Output is correct
2 Correct 116 ms 348 KB Output is correct
3 Correct 656 ms 348 KB Output is correct
4 Correct 378 ms 596 KB Output is correct
5 Correct 56 ms 412 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 256 ms 416 KB Output is correct
2 Correct 116 ms 348 KB Output is correct
3 Correct 656 ms 348 KB Output is correct
4 Correct 378 ms 596 KB Output is correct
5 Correct 56 ms 412 KB Output is correct
6 Correct 292 ms 428 KB Output is correct
7 Correct 145 ms 344 KB Output is correct
8 Correct 786 ms 436 KB Output is correct
9 Correct 383 ms 600 KB Output is correct
10 Correct 13 ms 348 KB Output is correct
11 Correct 19 ms 348 KB Output is correct
12 Correct 710 ms 420 KB Output is correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 256 ms 416 KB Output is correct
2 Correct 116 ms 348 KB Output is correct
3 Correct 656 ms 348 KB Output is correct
4 Correct 378 ms 596 KB Output is correct
5 Correct 56 ms 412 KB Output is correct
6 Correct 292 ms 428 KB Output is correct
7 Correct 145 ms 344 KB Output is correct
8 Correct 786 ms 436 KB Output is correct
9 Correct 383 ms 600 KB Output is correct
10 Correct 13 ms 348 KB Output is correct
11 Correct 19 ms 348 KB Output is correct
12 Correct 710 ms 420 KB Output is correct
13 Partially correct 292 ms 592 KB Output is partially correct
14 Partially correct 132 ms 520 KB Output is partially correct
15 Partially correct 910 ms 520 KB Output is partially correct
16 Partially correct 457 ms 520 KB Output is partially correct
17 Incorrect 3 ms 348 KB Output isn't correct
18 Halted 0 ms 0 KB -