oj.uz

Submission #1005550

# Submission time Handle Problem Language Result Execution time Memory
1005550 2024-06-22T15:31:23 Z anango Necklace (Subtask 1-3) (BOI19_necklace1) C++17
45 / 85
 539 ms 492 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<1000000; 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 125 ms 344 KB Output is correct
2 Correct 68 ms 348 KB Output is correct
3 Correct 362 ms 344 KB Output is correct
4 Correct 192 ms 348 KB Output is correct
5 Correct 28 ms 344 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 125 ms 344 KB Output is correct
2 Correct 68 ms 348 KB Output is correct
3 Correct 362 ms 344 KB Output is correct
4 Correct 192 ms 348 KB Output is correct
5 Correct 28 ms 344 KB Output is correct
6 Correct 133 ms 428 KB Output is correct
7 Correct 69 ms 436 KB Output is correct
8 Correct 408 ms 436 KB Output is correct
9 Correct 191 ms 428 KB Output is correct
10 Correct 7 ms 344 KB Output is correct
11 Correct 10 ms 348 KB Output is correct
12 Correct 342 ms 420 KB Output is correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 125 ms 344 KB Output is correct
2 Correct 68 ms 348 KB Output is correct
3 Correct 362 ms 344 KB Output is correct
4 Correct 192 ms 348 KB Output is correct
5 Correct 28 ms 344 KB Output is correct
6 Correct 133 ms 428 KB Output is correct
7 Correct 69 ms 436 KB Output is correct
8 Correct 408 ms 436 KB Output is correct
9 Correct 191 ms 428 KB Output is correct
10 Correct 7 ms 344 KB Output is correct
11 Correct 10 ms 348 KB Output is correct
12 Correct 342 ms 420 KB Output is correct
13 Partially correct 148 ms 348 KB Output is partially correct
14 Correct 68 ms 348 KB Output is correct
15 Partially correct 539 ms 492 KB Output is partially correct
16 Partially correct 254 ms 344 KB Output is partially correct
17 Incorrect 3 ms 348 KB Output isn't correct
18 Halted 0 ms 0 KB -