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  1. #include <bits/stdc++.h> 
  2.  
  3. using namespace std;  
  4.  
  5. typedef long long ll;  
  6. typedef pair<int, int> ii;  
  7.  
  8. const int INF = 1e9;  
  9. const ll LINF = 1e18;  
  10.  
  11. const int MOD = 1e9 + 7; 
  12. const int N = 2e3 + 5; 
  13.  
  14. void add(int& a, int b) {
  15. 	a = (0LL + a + b) % MOD; 
  16. 	if (a < 0) a += MOD; 
  17. }
  18.  
  19. int n, m; 
  20. int s[N], t[N];
  21.  
  22. int dp[N][N]; // dp[i][j] = Số xâu con chung khác rỗng của s[1..i] và t[1..j]
  23.  
  24. int main() {
  25. 	ios::sync_with_stdio(false); 
  26. 	cin.tie(nullptr); 	
  27. 	cin >> n >> m; 
  28. 	for (int i = 1; i <= n; i++) cin >> s[i]; 
  29. 	for (int i = 1; i <= m; i++) cin >> t[i]; 
  30.  
  31. 	for (int i = 1; i <= n; i++) {
  32. 		for (int j = 1; j <= m; j++) {
  33. 			if (s[i] == t[j]) add(dp[i][j], 1 + dp[i - 1][j - 1]); 
  34. 			add(dp[i][j], dp[i - 1][j] + dp[i][j - 1] - dp[i - 1][j - 1]); 
  35. 		}
  36. 	}
  37.  
  38. 	int ans = dp[n][m]; 
  39. 	add(ans, 1); 
  40.  
  41. 	cout << ans << '\n'; 
  42. }
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/kq1jym
language:
C++14 (gcc 8.3)
created:
1 year ago
visibility:
secret

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