You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
49 lines
1.6 KiB
49 lines
1.6 KiB
"""
|
|
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:
|
|
"""Coin change: Greedy"""
|
|
# Assume coins list is ordered
|
|
i = len(coins) - 1
|
|
count = 0
|
|
# Loop for greedy selection until no remaining amount
|
|
while amt > 0:
|
|
# Find the smallest coin close to and less than the remaining amount
|
|
while i > 0 and coins[i] > amt:
|
|
i -= 1
|
|
# Choose coins[i]
|
|
amt -= coins[i]
|
|
count += 1
|
|
# If no feasible solution is found, return -1
|
|
return count if amt == 0 else -1
|
|
|
|
|
|
"""Driver Code"""
|
|
if __name__ == "__main__":
|
|
# Greedy: can ensure finding a global optimal solution
|
|
coins = [1, 5, 10, 20, 50, 100]
|
|
amt = 186
|
|
res = coin_change_greedy(coins, amt)
|
|
print(f"\ncoins = {coins}, amt = {amt}")
|
|
print(f"The minimum number of coins needed to make up {amt} is {res}")
|
|
|
|
# Greedy: cannot ensure finding a global optimal solution
|
|
coins = [1, 20, 50]
|
|
amt = 60
|
|
res = coin_change_greedy(coins, amt)
|
|
print(f"\ncoins = {coins}, amt = {amt}")
|
|
print(f"The minimum number of coins needed to make up {amt} is {res}")
|
|
print(f"In reality, the minimum number needed is 3, i.e., 20 + 20 + 20")
|
|
|
|
# Greedy: cannot ensure finding a global optimal solution
|
|
coins = [1, 49, 50]
|
|
amt = 98
|
|
res = coin_change_greedy(coins, amt)
|
|
print(f"\ncoins = {coins}, amt = {amt}")
|
|
print(f"The minimum number of coins needed to make up {amt} is {res}")
|
|
print(f"In reality, the minimum number needed is 2, i.e., 49 + 49")
|