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답안 #1005552

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
1005552 2024-06-22T15:31:52 Z anango Necklace (Subtask 1-3) (BOI19_necklace1) C++17
45 / 85
 1331 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<=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

# 결과 실행 시간 메모리 Grader output
1 Correct 387 ms 412 KB Output is correct
2 Correct 194 ms 348 KB Output is correct
3 Correct 1066 ms 344 KB Output is correct
4 Correct 572 ms 344 KB Output is correct
5 Correct 77 ms 344 KB Output is correct

Subtask #2
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 387 ms 412 KB Output is correct
2 Correct 194 ms 348 KB Output is correct
3 Correct 1066 ms 344 KB Output is correct
4 Correct 572 ms 344 KB Output is correct
5 Correct 77 ms 344 KB Output is correct
6 Correct 379 ms 348 KB Output is correct
7 Correct 223 ms 344 KB Output is correct
8 Correct 1086 ms 440 KB Output is correct
9 Correct 559 ms 596 KB Output is correct
10 Correct 17 ms 348 KB Output is correct
11 Correct 28 ms 348 KB Output is correct
12 Correct 1025 ms 436 KB Output is correct

Subtask #3
0.0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 387 ms 412 KB Output is correct
2 Correct 194 ms 348 KB Output is correct
3 Correct 1066 ms 344 KB Output is correct
4 Correct 572 ms 344 KB Output is correct
5 Correct 77 ms 344 KB Output is correct
6 Correct 379 ms 348 KB Output is correct
7 Correct 223 ms 344 KB Output is correct
8 Correct 1086 ms 440 KB Output is correct
9 Correct 559 ms 596 KB Output is correct
10 Correct 17 ms 348 KB Output is correct
11 Correct 28 ms 348 KB Output is correct
12 Correct 1025 ms 436 KB Output is correct
13 Partially correct 402 ms 496 KB Output is partially correct
14 Correct 208 ms 348 KB Output is correct
15 Partially correct 1331 ms 524 KB Output is partially correct
16 Partially correct 637 ms 520 KB Output is partially correct
17 Incorrect 5 ms 344 KB Output isn't correct
18 Halted 0 ms 0 KB -