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Submission #203617

# Submission time Handle Problem Language Result Execution time Memory
203617 2020-02-21T15:35:31 Z stefdasca Kangaroo (CEOI16_kangaroo) C++14
51 / 100
 2000 ms 31740 KB 
#include<bits/stdc++.h>
#define mod 1000000007
using namespace std;
int n, a, b;
inline int add(int a, int b)
{
    if(!b)
        return a;
    int x = a+b;
    if(x >= mod)
        x -= mod;
    else
        if(x < 0)
            x += mod;
    return x;
}
int dp[2][2002][2002];
int sp[2][2][2002][2002];
int main()
{
    cin >> n >> a >> b;
    for(int i = 1; i <= n; ++i)
        if(i != a && i != b)
            dp[(a < i)][i - 1 - (a < i)][b - (a < b) - (i < b)] = 1;
    if(n == 2)
    {
        cout << 1;
        return 0;
    }
    int ans = 0;
    for(int sum = n-2; sum >= 1; --sum)
    {
        for(int i = 0; i <= sum; ++i)
            for(int pos = 1; pos <= sum; ++pos)
            {
                int smaller = i;
                int bigger = sum - i;
                if(sum != n-2)
                {
                    dp[0][smaller][pos] = add(sp[0][0][smaller][pos], (smaller > 0) * dp[0][smaller - 1][pos]);
                    dp[1][smaller][pos] = add(sp[0][1][smaller][pos], (smaller > 0) * dp[1][smaller - 1][pos]);
                }
                if(!dp[0][smaller][pos] && !dp[1][smaller][pos])
                    continue;
             //   cout << sum << '\n';
               // cout << smaller << " " << bigger << " " << pos << '\n';
               // cout << dp[0][smaller][bigger][pos] << " " << dp[1][smaller][bigger][pos] << '\n';
                if(sum == 1)
                {
                    if(smaller)
                        ans = add(ans, dp[1][smaller][1]);
                    else
                        ans = add(ans, dp[0][smaller][1]);
                }
                else
                {
                    if(pos <= smaller)
                    {
                        if(pos != 1)
                        {
                            sp[1][0][0][pos - 1] = add(sp[1][0][0][pos - 1], dp[1][smaller][pos]);
                            sp[1][0][pos - 1][pos - 1] = add(sp[1][0][pos - 1][pos - 1], -dp[1][smaller][pos]);
                        }

                        if(pos != smaller)
                        {
                            sp[1][0][pos][pos] = add(sp[1][0][pos][pos], dp[1][smaller][pos]);
                            sp[1][0][smaller][pos] = add(sp[1][0][smaller][pos], -dp[1][smaller][pos]);
                        }

                        if(smaller != sum)
                        {
                            sp[1][1][smaller][pos] = add(sp[1][1][smaller][pos], dp[0][smaller][pos]);
                            sp[1][1][sum][pos] = add(sp[1][1][sum][pos], -dp[0][smaller][pos]);
                        }
                    }
                    else
                    {
                        if(pos != smaller)
                        {
                            sp[1][0][0][pos - 1] = add(sp[1][0][0][pos - 1], dp[1][smaller][pos]);
                            sp[1][0][smaller][pos - 1] = add(sp[1][0][smaller][pos - 1], -dp[1][smaller][pos]);
                        }

                        if(pos - 1 != smaller)
                        {
                            sp[1][1][smaller][pos - 1] = add(sp[1][1][smaller][pos - 1], dp[0][smaller][pos]);
                            sp[1][1][pos - 1][pos - 1] = add(sp[1][1][pos - 1][pos - 1], -dp[0][smaller][pos]);
                        }

                        if(pos != sum)
                        {
                            sp[1][1][pos][pos] = add(sp[1][1][pos][pos], dp[0][smaller][pos]);
                            sp[1][1][sum][pos] = add(sp[1][1][sum][pos], -dp[0][smaller][pos]);
                        }
                    }
                }
            }
        for(int x = 0; x <= 1; ++x)
            for(int q = 0; q <= sum; ++q)
            {
                memcpy(sp[0][x][q], sp[1][x][q], 4 * (sum + 1));
                memset(sp[1][x][q], 0, 4 * (sum + 1));
              //  for(int p = 0; p <= sum; ++p)
                //    sp[0][x][q][p] = sp[1][x][q][p], sp[1][x][q][p] = 0;
            }
    }
    cout << ans;
    return 0;
}

Compilation message

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:37:21: warning: unused variable 'bigger' [-Wunused-variable]
                 int bigger = sum - i;
                     ^~~~~~

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 376 KB Output is correct
2 Correct 5 ms 508 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 376 KB Output is correct
2 Correct 5 ms 508 KB Output is correct
3 Correct 5 ms 888 KB Output is correct
4 Correct 6 ms 1272 KB Output is correct
5 Correct 6 ms 1272 KB Output is correct
6 Correct 5 ms 1276 KB Output is correct
7 Correct 5 ms 1272 KB Output is correct
8 Correct 6 ms 1272 KB Output is correct
9 Correct 6 ms 1272 KB Output is correct
10 Correct 5 ms 1272 KB Output is correct
11 Correct 6 ms 1272 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 376 KB Output is correct
2 Correct 5 ms 508 KB Output is correct
3 Correct 5 ms 888 KB Output is correct
4 Correct 6 ms 1272 KB Output is correct
5 Correct 6 ms 1272 KB Output is correct
6 Correct 5 ms 1276 KB Output is correct
7 Correct 5 ms 1272 KB Output is correct
8 Correct 6 ms 1272 KB Output is correct
9 Correct 6 ms 1272 KB Output is correct
10 Correct 5 ms 1272 KB Output is correct
11 Correct 6 ms 1272 KB Output is correct
12 Correct 45 ms 6008 KB Output is correct
13 Correct 33 ms 5624 KB Output is correct
14 Correct 20 ms 6012 KB Output is correct
15 Correct 44 ms 6008 KB Output is correct
16 Correct 20 ms 6008 KB Output is correct
17 Correct 47 ms 6008 KB Output is correct
18 Correct 22 ms 5344 KB Output is correct
19 Correct 46 ms 6008 KB Output is correct
20 Correct 47 ms 6008 KB Output is correct

Subtask #4
0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 376 KB Output is correct
2 Correct 5 ms 508 KB Output is correct
3 Correct 5 ms 888 KB Output is correct
4 Correct 6 ms 1272 KB Output is correct
5 Correct 6 ms 1272 KB Output is correct
6 Correct 5 ms 1276 KB Output is correct
7 Correct 5 ms 1272 KB Output is correct
8 Correct 6 ms 1272 KB Output is correct
9 Correct 6 ms 1272 KB Output is correct
10 Correct 5 ms 1272 KB Output is correct
11 Correct 6 ms 1272 KB Output is correct
12 Correct 45 ms 6008 KB Output is correct
13 Correct 33 ms 5624 KB Output is correct
14 Correct 20 ms 6012 KB Output is correct
15 Correct 44 ms 6008 KB Output is correct
16 Correct 20 ms 6008 KB Output is correct
17 Correct 47 ms 6008 KB Output is correct
18 Correct 22 ms 5344 KB Output is correct
19 Correct 46 ms 6008 KB Output is correct
20 Correct 47 ms 6008 KB Output is correct
21 Correct 1516 ms 26464 KB Output is correct
22 Correct 1706 ms 28664 KB Output is correct
23 Execution timed out 2095 ms 31740 KB Time limit exceeded
24 Halted 0 ms 0 KB -