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답안 #1005561

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
1005561 2024-06-22T15:39:20 Z anango Necklace (Subtask 1-3) (BOI19_necklace1) C++17
45 / 85
 1500 ms 676 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<7000000; 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};
        }
        if (subans<=ans/2) {
            continue;
        }
        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
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 621 ms 344 KB Output is correct
2 Correct 296 ms 412 KB Output is correct
3 Correct 851 ms 600 KB Output is correct
4 Correct 487 ms 344 KB Output is correct
5 Correct 75 ms 348 KB Output is correct

Subtask #2
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 621 ms 344 KB Output is correct
2 Correct 296 ms 412 KB Output is correct
3 Correct 851 ms 600 KB Output is correct
4 Correct 487 ms 344 KB Output is correct
5 Correct 75 ms 348 KB Output is correct
6 Correct 638 ms 432 KB Output is correct
7 Correct 316 ms 436 KB Output is correct
8 Correct 597 ms 432 KB Output is correct
9 Correct 305 ms 348 KB Output is correct
10 Correct 15 ms 344 KB Output is correct
11 Correct 18 ms 348 KB Output is correct
12 Correct 1101 ms 676 KB Output is correct

Subtask #3
0.0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 621 ms 344 KB Output is correct
2 Correct 296 ms 412 KB Output is correct
3 Correct 851 ms 600 KB Output is correct
4 Correct 487 ms 344 KB Output is correct
5 Correct 75 ms 348 KB Output is correct
6 Correct 638 ms 432 KB Output is correct
7 Correct 316 ms 436 KB Output is correct
8 Correct 597 ms 432 KB Output is correct
9 Correct 305 ms 348 KB Output is correct
10 Correct 15 ms 344 KB Output is correct
11 Correct 18 ms 348 KB Output is correct
12 Correct 1101 ms 676 KB Output is correct
13 Correct 600 ms 636 KB Output is correct
14 Partially correct 327 ms 344 KB Output is partially correct
15 Partially correct 856 ms 488 KB Output is partially correct
16 Correct 283 ms 596 KB Output is correct
17 Correct 4 ms 348 KB Output is correct
18 Correct 20 ms 552 KB Output is correct
19 Partially correct 303 ms 504 KB Output is partially correct
20 Partially correct 1328 ms 500 KB Output is partially correct
21 Execution timed out 1523 ms 344 KB Time limit exceeded
22 Halted 0 ms 0 KB -