Submission #698869

#	Time	Username	Problem	Language	Result	Execution time	Memory
698869		dattranxxx	Kangaroo (CEOI16_kangaroo)	C++11	51 / 100	2090 ms	154304 KiB

kangaroo

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
 
const int N = 505;
int A[N][N][N], D[N][N][N];
 
const int M = 1e9 + 7;
void add(int& x, int y) { x += y; if (x >= M) x -= M; }
void sub(int& x, int y) { x -= y; if (x < 0) x += M; }
int sum(int x, int y) { x += y; if (x >= M) x -= M; return x; }
int dif(int x, int y) { x -= y; if (x < 0) x += M; return x; }

int n, s, t;
 
int main() {
  cin.tie(0)->sync_with_stdio(0); cout.tie(0);
  cin >> n >> s >> t; 
  
  A[2][1][2] = D[2][2][1] = 1;
  for (int i = 3; i <= n; ++i) {
    for (int s = 1; s <= i; ++s) {
      for (int t = 1; t <= i; ++t) {
        if (s == t) continue;
          
        if (s < t) {
          for (int j = s; j <= i - 1; ++j) {
            add(A[i][s][t], D[i - 1][j][t - 1]);
          }
          
          for (int j = 1; j < s; ++j) {
            add(D[i][s][t], A[i - 1][j][t - 1]);
          }
        } else {
          for (int j = s; j <= i - 1; ++j) {
            add(A[i][s][t], D[i - 1][j][t]);
          }
          
          for (int j = 1; j < s; ++j) {
            add(D[i][s][t], A[i - 1][j][t]);
          }
        }
        
        // cerr << i << ' ' << s << ' ' << t << ' ' << A[i][s][t] << ' ' << D[i][s][t] << '\n';
        
      }
    }
  }
  
  add(A[n][s][t], D[n][s][t]);
  cout << A[n][s][t];
 
	return 0;
}

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 0 / 49