[못 푼 문제] 백준 2225번

생각을 깊게 못했다.

d(n, k) = d(n, k-1) + d(n-1, k-1) + ... + d(1, k-1) + d(0, k-1)
= d(n, k-1) + d(n-1, k)

n, k = map(int, input().split())
d = []
for _ in range(201):
    d.append([1 for i in range(201)])

for i in range(1, n+1):
    for j in range(2, k+1):
        d[i][j] = d[i-1][j] + d[i][j-1]

print(d[n][k] % 1000000000)