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Submission #54402

# Submission time Handle Problem Language Result Execution time Memory
54402 2018-07-03T10:20:26 Z zadrga Kangaroo (CEOI16_kangaroo) C++14
100 / 100
 49 ms 33980 KB 
#include <bits/stdc++.h>

using namespace std;

#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define INF (1LL << 55)
#define MOD (1000 * 1000 * 1000 + 7)
#define maxn 2111

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;

ll dp[maxn][maxn];	// dp[first x elements already distributed][number of groups]

int main(){
	int n, s, e;
	scanf("%d%d%d", &n, &s, &e);

	int cnt = 0;
	dp[0][0] = 1;
	for(int i = 1; i <= n; i++){
		for(int j = 1; j <= n; j++){
			if(i == e || i == s){		// merge with first/last group + add a new group
				dp[i][j] = (dp[i - 1][j] + dp[i - 1][j - 1]) % MOD;
			}
			else{						// add a new group between 2 groups (x + 1 free spaces - start/end positions) + join two groups (x - 1 free spaces between)
				dp[i][j] = (dp[i - 1][j - 1] * ((j - 1) + 1 - cnt) + dp[i - 1][j + 1] * ((j + 1) - 1)) % MOD;
			}
		}
		if(i == e || i == s)
			cnt++;
	}

	printf("%lld\n", dp[n][1]);
	return 0;
}

Compilation message

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:21:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d", &n, &s, &e);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 248 KB Output is correct
2 Correct 2 ms 360 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 248 KB Output is correct
2 Correct 2 ms 360 KB Output is correct
3 Correct 2 ms 528 KB Output is correct
4 Correct 2 ms 640 KB Output is correct
5 Correct 2 ms 644 KB Output is correct
6 Correct 2 ms 696 KB Output is correct
7 Correct 2 ms 760 KB Output is correct
8 Correct 2 ms 764 KB Output is correct
9 Correct 2 ms 784 KB Output is correct
10 Correct 2 ms 788 KB Output is correct
11 Correct 2 ms 844 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 248 KB Output is correct
2 Correct 2 ms 360 KB Output is correct
3 Correct 2 ms 528 KB Output is correct
4 Correct 2 ms 640 KB Output is correct
5 Correct 2 ms 644 KB Output is correct
6 Correct 2 ms 696 KB Output is correct
7 Correct 2 ms 760 KB Output is correct
8 Correct 2 ms 764 KB Output is correct
9 Correct 2 ms 784 KB Output is correct
10 Correct 2 ms 788 KB Output is correct
11 Correct 2 ms 844 KB Output is correct
12 Correct 3 ms 1744 KB Output is correct
13 Correct 2 ms 1776 KB Output is correct
14 Correct 3 ms 1792 KB Output is correct
15 Correct 3 ms 1800 KB Output is correct
16 Correct 3 ms 1800 KB Output is correct
17 Correct 4 ms 1804 KB Output is correct
18 Correct 3 ms 1808 KB Output is correct
19 Correct 3 ms 1832 KB Output is correct
20 Correct 3 ms 1832 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 248 KB Output is correct
2 Correct 2 ms 360 KB Output is correct
3 Correct 2 ms 528 KB Output is correct
4 Correct 2 ms 640 KB Output is correct
5 Correct 2 ms 644 KB Output is correct
6 Correct 2 ms 696 KB Output is correct
7 Correct 2 ms 760 KB Output is correct
8 Correct 2 ms 764 KB Output is correct
9 Correct 2 ms 784 KB Output is correct
10 Correct 2 ms 788 KB Output is correct
11 Correct 2 ms 844 KB Output is correct
12 Correct 3 ms 1744 KB Output is correct
13 Correct 2 ms 1776 KB Output is correct
14 Correct 3 ms 1792 KB Output is correct
15 Correct 3 ms 1800 KB Output is correct
16 Correct 3 ms 1800 KB Output is correct
17 Correct 4 ms 1804 KB Output is correct
18 Correct 3 ms 1808 KB Output is correct
19 Correct 3 ms 1832 KB Output is correct
20 Correct 3 ms 1832 KB Output is correct
21 Correct 7 ms 6828 KB Output is correct
22 Correct 8 ms 7344 KB Output is correct
23 Correct 8 ms 8244 KB Output is correct
24 Correct 33 ms 33800 KB Output is correct
25 Correct 34 ms 33980 KB Output is correct
26 Correct 49 ms 33980 KB Output is correct
27 Correct 33 ms 33980 KB Output is correct
28 Correct 23 ms 33980 KB Output is correct