mirror of
https://github.com/krahets/hello-algo.git
synced 2024-12-26 23:46:29 +08:00
49 lines
1.5 KiB
Python
49 lines
1.5 KiB
Python
|
"""
|
||
|
|
File: coin_change_greedy.py
|
||
|
|
Created Time: 2023-07-18
|
||
|
|
Author: krahets (krahets@163.com)
|
||
|
|
"""
|
||
|
|
|
||
|
|
|
||
|
|
def coin_change_greedy(coins: list[int], amt: int) -> int:
|
||
|
|
"""零錢兌換：貪婪"""
|
||
|
|
# 假設 coins 串列有序
|
||
|
|
i = len(coins) - 1
|
||
|
|
count = 0
|
||
|
|
# 迴圈進行貪婪選擇，直到無剩餘金額
|
||
|
|
while amt > 0:
|
||
|
|
# 找到小於且最接近剩餘金額的硬幣
|
||
|
|
while i > 0 and coins[i] > amt:
|
||
|
|
i -= 1
|
||
|
|
# 選擇 coins[i]
|
||
|
|
amt -= coins[i]
|
||
|
|
count += 1
|
||
|
|
# 若未找到可行方案，則返回 -1
|
||
|
|
return count if amt == 0 else -1
|
||
|
|
|
||
|
|
|
||
|
|
"""Driver Code"""
|
||
|
|
if __name__ == "__main__":
|
||
|
|
# 貪婪：能夠保證找到全域性最優解
|
||
|
|
coins = [1, 5, 10, 20, 50, 100]
|
||
|
|
amt = 186
|
||
|
|
res = coin_change_greedy(coins, amt)
|
||
|
|
print(f"\ncoins = {coins}, amt = {amt}")
|
||
|
|
print(f"湊到 {amt} 所需的最少硬幣數量為 {res}")
|
||
|
|
|
||
|
|
# 貪婪：無法保證找到全域性最優解
|
||
|
|
coins = [1, 20, 50]
|
||
|
|
amt = 60
|
||
|
|
res = coin_change_greedy(coins, amt)
|
||
|
|
print(f"\ncoins = {coins}, amt = {amt}")
|
||
|
|
print(f"湊到 {amt} 所需的最少硬幣數量為 {res}")
|
||
|
|
print(f"實際上需要的最少數量為 3 ，即 20 + 20 + 20")
|
||
|
|
|
||
|
|
# 貪婪：無法保證找到全域性最優解
|
||
|
|
coins = [1, 49, 50]
|
||
|
|
amt = 98
|
||
|
|
res = coin_change_greedy(coins, amt)
|
||
|
|
print(f"\ncoins = {coins}, amt = {amt}")
|
||
|
|
print(f"湊到 {amt} 所需的最少硬幣數量為 {res}")
|
||
|
|
print(f"實際上需要的最少數量為 2 ，即 49 + 49")
|