oj.uz

Submission #1005553

# Submission time Handle Problem Language Result Execution time Memory
1005553 2024-06-22T15:33:56 Z anango Necklace (Subtask 1-3) (BOI19_necklace1) C++17
9 / 85
 383 ms 596 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 185 ms 596 KB Output is correct
2 Partially correct 90 ms 348 KB Output is partially correct
3 Correct 299 ms 348 KB Output is correct
4 Correct 159 ms 420 KB Output is correct
5 Partially correct 32 ms 348 KB Output is partially correct

Subtask #2
4.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 185 ms 596 KB Output is correct
2 Partially correct 90 ms 348 KB Output is partially correct
3 Correct 299 ms 348 KB Output is correct
4 Correct 159 ms 420 KB Output is correct
5 Partially correct 32 ms 348 KB Output is partially correct
6 Partially correct 195 ms 420 KB Output is partially correct
7 Correct 86 ms 344 KB Output is correct
8 Partially correct 317 ms 348 KB Output is partially correct
9 Correct 169 ms 348 KB Output is correct
10 Correct 7 ms 348 KB Output is correct
11 Correct 9 ms 344 KB Output is correct
12 Correct 329 ms 420 KB Output is correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 185 ms 596 KB Output is correct
2 Partially correct 90 ms 348 KB Output is partially correct
3 Correct 299 ms 348 KB Output is correct
4 Correct 159 ms 420 KB Output is correct
5 Partially correct 32 ms 348 KB Output is partially correct
6 Partially correct 195 ms 420 KB Output is partially correct
7 Correct 86 ms 344 KB Output is correct
8 Partially correct 317 ms 348 KB Output is partially correct
9 Correct 169 ms 348 KB Output is correct
10 Correct 7 ms 348 KB Output is correct
11 Correct 9 ms 344 KB Output is correct
12 Correct 329 ms 420 KB Output is correct
13 Partially correct 185 ms 492 KB Output is partially correct
14 Correct 104 ms 496 KB Output is correct
15 Partially correct 383 ms 492 KB Output is partially correct
16 Partially correct 183 ms 476 KB Output is partially correct
17 Incorrect 2 ms 344 KB Output isn't correct
18 Halted 0 ms 0 KB -