70. 爬楼梯 （进阶）
322. 零钱兑换
class Solution:
def climbStairs(self, n: int) -> int:
if n <= 1:
return n
dp = [0] * (n + 1)
dp[0] = 0
dp[1] = 1
dp[2] = 2
for i in range(3, n + 1):
dp[i] = dp[i - 1] + dp[i - 2]
return dp[n]
279.完全平方数
class Solution:
def numSquares(self, n: int) -> int:
dp = [float('inf')] * (n + 1)
dp[0] = 0
for i in range(1, int(n ** 0.5) + 1):
for j in range(i * i, n + 1):
dp[j] = min(dp[j], dp[j - i * i] + 1)
return dp[n]
