hdoj：2067

根據公式計算卡特蘭數，始終出現越界，本身沒法解決

#include <iostream>

using namespace std;

long long Catalan(int num)
{
    long long result = 1;
    for (int i = 1; i <= num; i++)
        result *= (i + num);
    for (int i = 1; i <= num; i++)
        result /= i;
    result /= (num + 1);
    return (long long)result;
}
int main()
{
    int num;
    int i = 1;
    while (cin >> num && num != -1)
    {
        printf("%d %d %I64d\n", i++, num, 2 * Catalan(num));
        
    }
}

根據遞推公式

動態規劃

#include <iostream>

using namespace std;

long long dp[36][36];
int main()
{
    
    int num;
    
    int i = 1;
    for (int i = 0; i <= 35; i++)
        dp[i][0] = 1;
    for (int i = 1; i <= 35; i++)
    {
        for (int j = 0; j <= i; j++)
        {
            if (i == j)
                dp[i][j] = dp[i][j - 1];
            else
                dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
        }
    }
    while (cin >> num && num != -1)
    {
        printf("%d %d %I64d\n", i++, num, 2 * dp[num][num]);
        
    }
}