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Submission #197123

# Submission time Handle Problem Language Result Execution time Memory
197123 2020-01-19T02:47:47 Z arnold518 Necklace (Subtask 1-3) (BOI19_necklace1) C++14
45 / 85
 1500 ms 536 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 3000;
const ll MOD = 1e9+7;
const ll P = 31;

ll mypow(ll x, ll y)
{
	if(y==0) return 1;
	if(y%2) return mypow(x, y-1)*x%MOD;
	ll ret=mypow(x, y/2);
	return ret*ret%MOD;
}

ll inv(ll x) { return mypow(x, MOD-2); }

int N, M, ans, ans1, ans2;
char S[MAXN+10], T[MAXN+10];
ll HS[MAXN+10], HT[MAXN+10];
ll ppow[MAXN+10], pinv[MAXN+10];

ll hashval(ll *H, int l, int r)
{
	ll ret=H[r]-H[l];
	ret=(ret%MOD+MOD)%MOD;
	ret=ret*pinv[l]%MOD;
	return ret;
}

int main()
{
	int i, j, k;
	scanf("%s%s", S+1, T+1);
	N=strlen(S+1); M=strlen(T+1);

	ppow[0]=1;
	for(i=1; i<=MAXN; i++) ppow[i]=ppow[i-1]*P%MOD;

	pinv[0]=1; pinv[1]=inv(P);
	for(i=2; i<=MAXN; i++) pinv[i]=pinv[i-1]*pinv[1]%MOD;

	for(i=1; i<=N; i++) HS[i]=(HS[i-1]+ppow[i]*(S[i]-'a'+1))%MOD;
	for(i=1; i<=M; i++) HT[i]=(HT[i-1]+ppow[i]*(T[i]-'a'+1))%MOD;

	for(i=1; i<=N; i++) for(j=1; j<=M; j++)
	{
		int p, q;

		for(k=min(i, M-j); k>=0; k--) if(hashval(HS, i-k, i)==hashval(HT, j, j+k)) break;
		p=k;

		for(k=min(N-i, j); k>=0; k--) if(hashval(HS, i, i+k)==hashval(HT, j-k, j)) break;
		q=k;

		if(p+q>ans) ans=p+q, ans1=i-p, ans2=j-q;
	}

	reverse(T+1, T+M+1);
	for(i=1; i<=N; i++) HS[i]=(HS[i-1]+ppow[i]*(S[i]-'a'+1))%MOD;
	for(i=1; i<=M; i++) HT[i]=(HT[i-1]+ppow[i]*(T[i]-'a'+1))%MOD;
	for(i=1; i<=N; i++) for(j=1; j<=M; j++)
	{
		int p, q;

		for(k=min(i, M-j); k>=0; k--) if(hashval(HS, i-k, i)==hashval(HT, j, j+k)) break;
		p=k;

		for(k=min(N-i, j); k>=0; k--) if(hashval(HS, i, i+k)==hashval(HT, j-k, j)) break;
		q=k;

		if(p+q>ans) ans=p+q, ans1=i-p, ans2=M-(j+p);
	}
	printf("%d\n%d %d\n", ans, ans1, ans2);
}

Compilation message

necklace.cpp: In function 'int main()':
necklace.cpp:38:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s%s", S+1, T+1);
  ~~~~~^~~~~~~~~~~~~~~~~~

Subtask #1
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 504 KB Output is correct
2 Correct 8 ms 376 KB Output is correct
3 Correct 9 ms 376 KB Output is correct
4 Correct 12 ms 376 KB Output is correct
5 Correct 17 ms 504 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 504 KB Output is correct
2 Correct 8 ms 376 KB Output is correct
3 Correct 9 ms 376 KB Output is correct
4 Correct 12 ms 376 KB Output is correct
5 Correct 17 ms 504 KB Output is correct
6 Correct 288 ms 464 KB Output is correct
7 Correct 479 ms 376 KB Output is correct
8 Correct 589 ms 532 KB Output is correct
9 Correct 750 ms 476 KB Output is correct
10 Correct 845 ms 504 KB Output is correct
11 Correct 876 ms 464 KB Output is correct
12 Correct 708 ms 536 KB Output is correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 504 KB Output is correct
2 Correct 8 ms 376 KB Output is correct
3 Correct 9 ms 376 KB Output is correct
4 Correct 12 ms 376 KB Output is correct
5 Correct 17 ms 504 KB Output is correct
6 Correct 288 ms 464 KB Output is correct
7 Correct 479 ms 376 KB Output is correct
8 Correct 589 ms 532 KB Output is correct
9 Correct 750 ms 476 KB Output is correct
10 Correct 845 ms 504 KB Output is correct
11 Correct 876 ms 464 KB Output is correct
12 Correct 708 ms 536 KB Output is correct
13 Execution timed out 1528 ms 376 KB Time limit exceeded
14 Halted 0 ms 0 KB -