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
/**
|
|
* File: coin_change_greedy.dart
|
|
* Created Time: 2023-08-11
|
|
* Author: liuyuxin (gvenusleo@gmail.com)
|
|
*/
|
|
|
|
/* 零錢兌換：貪婪 */
|
|
int coinChangeGreedy(List<int> coins, int amt) {
|
|
// 假設 coins 串列有序
|
|
int i = coins.length - 1;
|
|
int 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 && coins[i] > amt) {
|
|
i--;
|
|
}
|
|
// 選擇 coins[i]
|
|
amt -= coins[i];
|
|
count++;
|
|
}
|
|
// 若未找到可行方案，則返回 -1
|
|
return amt == 0 ? count : -1;
|
|
}
|
|
|
|
/* Driver Code */
|
|
void main() {
|
|
// 貪婪：能夠保證找到全域性最優解
|
|
List<int> coins = [1, 5, 10, 20, 50, 100];
|
|
int amt = 186;
|
|
int res = coinChangeGreedy(coins, amt);
|
|
print("\ncoins = $coins, amt = $amt");
|
|
print("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 = coinChangeGreedy(coins, amt);
|
|
print("\ncoins = $coins, amt = $amt");
|
|
print("湊到 $amt 所需的最少硬幣數量為 $res");
|
|
print("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 = coinChangeGreedy(coins, amt);
|
|
print("\ncoins = $coins, amt = $amt");
|
|
print("湊到 $amt 所需的最少硬幣數量為 $res");
|
|
print("實際上需要的最少數量為 2 ，即 49 + 49");
|
|
}
|