3689616_wa.cpp

北大大牛代码 1240道题的原代码 超级权威

#include <stdio.h>
#include <string>

using namespace std;

int dp[21][21];
int cnt[21];

int init(int n)
{
	int i, j;

	dp[n][n] = 1;
	for (i = n - 1; i > 0; i--)
	{
		dp[i][n] = 1;
		for (j = n - 1; j > i; j--)
		{
			dp[i][j] = dp[i + 1][j] + dp[i][j + 1];
		}
		dp[i][i] = dp[i][i + 1];
	}
	return dp[1][1];
}

string find(int n, int rank)
{
	for (int j = 1; j <= n; j++)
	{
		if (cnt[j] * cnt[n - j] > rank)
		{
			return "E" + find(n - j, rank / cnt[j]) + "S" + find(j, rank / cnt[n - j]);
		}
		else
		{
			rank -= cnt[j] * cnt[n - j];
		}
	}
	return "";
}

int main()
{
	int n, m, i;

	for (i = 1; i <= 20; i++)
	{
		cnt[i] = init(i);
	}
	while (scanf("%d%d", &n, &m) == 2)
	{
		if (n == 0 && m == 0)
		{
			break;
		}
		if (m > cnt[n])
		{
			puts("ERROR");
			continue;
		}
		puts(find(n, m - 1).c_str());
	}
	return 0;
}