atcoder 競プロ典型90問 050 - Stair Jump（★3）
2022.12.13
問題
https://atcoder.jp/contests/typical90/tasks/typical90_ax
方針
- dp
- 条件分岐だけ注意
i-lが0以上なら、dp[i] = dp[i-1] + dp[i-l]i-lが0未満なら、dp[i] = dp[i-1]
n, l = map(int, input().split())
dp = [0 for _ in range(n + 1)]
dp[0] = 1
dp[1] = 1
for i in range(2, n + 1):
if i - l >= 0:
dp[i] = dp[i-1] + dp[i-l]
else:
dp[i] = dp[i-1]
print(dp[n] % (pow(10, 9) + 7))
