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.
51 lines
1.4 KiB
51 lines
1.4 KiB
=begin
|
|
File: coin_change_greedy.rb
|
|
Created Time: 2024-05-07
|
|
Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
|
|
=end
|
|
|
|
### 零钱兑换：贪心 ###
|
|
def coin_change_greedy(coins, amt)
|
|
# 假设 coins 列表有序
|
|
i = coins.length - 1
|
|
count = 0
|
|
# 循环进行贪心选择，直到无剩余金额
|
|
while amt > 0
|
|
# 找到小于且最接近剩余金额的硬币
|
|
while i > 0 && coins[i] > amt
|
|
i -= 1
|
|
end
|
|
# 选择 coins[i]
|
|
amt -= coins[i]
|
|
count += 1
|
|
end
|
|
# 若未找到可行方案， 则返回 -1
|
|
amt == 0 ? count : -1
|
|
end
|
|
|
|
### Driver Code ###
|
|
if __FILE__ == $0
|
|
# 贪心：能够保证找到全局最优解
|
|
coins = [1, 5, 10, 20, 50, 100]
|
|
amt = 186
|
|
res = coin_change_greedy(coins, amt)
|
|
puts "\ncoins = #{coins}, amt = #{amt}"
|
|
puts "凑到 #{amt} 所需的最少硬币数量为 #{res}"
|
|
|
|
# 贪心：无法保证找到全局最优解
|
|
coins = [1, 20, 50]
|
|
amt = 60
|
|
res = coin_change_greedy(coins, amt)
|
|
puts "\ncoins = #{coins}, amt = #{amt}"
|
|
puts "凑到 #{amt} 所需的最少硬币数量为 #{res}"
|
|
puts "实际上需要的最少数量为 3 , 即 20 + 20 + 20"
|
|
|
|
# 贪心：无法保证找到全局最优解
|
|
coins = [1, 49, 50]
|
|
amt = 98
|
|
res = coin_change_greedy(coins, amt)
|
|
puts "\ncoins = #{coins}, amt = #{amt}"
|
|
puts "凑到 #{amt} 所需的最少硬币数量为 #{res}"
|
|
puts "实际上需要的最少数量为 2 , 即 49 + 49"
|
|
end
|