mirror of
https://github.com/krahets/hello-algo.git
synced 2024-12-26 02:06:30 +08:00
8d5e84f70a
* feat: add Swift codes for greedy_algorithm article * feat: add Swift codes for fractional_knapsack_problem article * feat: add Swift codes for max_capacity_problem article * feat: add Swift codes for max_product_cutting_problem article
54 lines
1.7 KiB
Swift
54 lines
1.7 KiB
Swift
/**
|
||
* File: coin_change_greedy.swift
|
||
* Created Time: 2023-09-03
|
||
* Author: nuomi1 (nuomi1@qq.com)
|
||
*/
|
||
|
||
/* 零钱兑换：贪心 */
|
||
func coinChangeGreedy(coins: [Int], amt: Int) -> Int {
|
||
// 假设 coins 列表有序
|
||
var i = coins.count - 1
|
||
var count = 0
|
||
var amt = amt
|
||
// 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
|
||
}
|
||
// 选择 coins[i]
|
||
amt -= coins[i]
|
||
count += 1
|
||
}
|
||
// 若未找到可行方案，则返回 -1
|
||
return amt == 0 ? count : -1
|
||
}
|
||
|
||
@main
|
||
enum CoinChangeGreedy {
|
||
/* Driver Code */
|
||
static func main() {
|
||
// 贪心：能够保证找到全局最优解
|
||
var coins = [1, 5, 10, 20, 50, 100]
|
||
var amt = 186
|
||
var res = coinChangeGreedy(coins: coins, amt: amt)
|
||
print("\ncoins = \(coins), amount = \(amt)")
|
||
print("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 = coinChangeGreedy(coins: coins, amt: amt)
|
||
print("\ncoins = \(coins), amount = \(amt)")
|
||
print("凑到 \(amt) 所需的最少硬币数量为 \(res)")
|
||
print("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 = coinChangeGreedy(coins: coins, amt: amt)
|
||
print("\ncoins = \(coins), amount = \(amt)")
|
||
print("凑到 \(amt) 所需的最少硬币数量为 \(res)")
|
||
print("实际上需要的最少数量为 2 ，即 49 + 49")
|
||
}
|
||
}
|