BOJ - 20152 - Game Addiction

import sys

def swap(A, B):
    C = B
    B = A
    A = C
    return A, B

def solution():
    H, N = map(int, sys.stdin.readline().split())
    if H == N:
        print(1)
        return

    if H > N:
        H, N = swap(H, N)

    maps = [[0 for _ in range(31)] for _ in range(31)]
    maps[H][H] = 1

    for i in range(H, N + 1):
        maps[H][i] = 1

    for i in range(H + 1, N + 1):
        for j in range(H + 1, N + 1):
            if i > j: continue
            else:
                maps[i][j] = maps[i - 1][j] + maps[i][j - 1]

    print(maps[N][N])

solution()

https://www.acmicpc.net/problem/20152