61 lines
1.8 KiB
C
61 lines
1.8 KiB
C
/**
|
|
* File: coin_change_greedy.c
|
|
* Created Time: 2023-09-07
|
|
* Author: lwbaptx (lwbaptx@gmail.com)
|
|
*/
|
|
|
|
#include "../utils/common.h"
|
|
|
|
/* Coin change: Greedy */
|
|
int coinChangeGreedy(int *coins, int size, int amt) {
|
|
// Assume coins list is ordered
|
|
int i = size - 1;
|
|
int 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 && coins[i] > amt) {
|
|
i--;
|
|
}
|
|
// Choose coins[i]
|
|
amt -= coins[i];
|
|
count++;
|
|
}
|
|
// If no feasible solution is found, return -1
|
|
return amt == 0 ? count : -1;
|
|
}
|
|
|
|
/* Driver Code */
|
|
int main() {
|
|
// Greedy: can ensure finding a global optimal solution
|
|
int coins1[6] = {1, 5, 10, 20, 50, 100};
|
|
int amt = 186;
|
|
int res = coinChangeGreedy(coins1, 6, amt);
|
|
printf("\ncoins = ");
|
|
printArray(coins1, 6);
|
|
printf("amt = %d\n", amt);
|
|
printf("To collect %d, the minimum number of coins required is %d\n", amt, res);
|
|
|
|
// Greedy: cannot ensure finding a global optimal solution
|
|
int coins2[3] = {1, 20, 50};
|
|
amt = 60;
|
|
res = coinChangeGreedy(coins2, 3, amt);
|
|
printf("\ncoins = ");
|
|
printArray(coins2, 3);
|
|
printf("amt = %d\n", amt);
|
|
printf("To collect %d, the minimum number of coins required is %d\n", amt, res);
|
|
printf("Actually, the minimum number required is 3, namely 20 + 20 + 20\n");
|
|
|
|
// Greedy: cannot ensure finding a global optimal solution
|
|
int coins3[3] = {1, 49, 50};
|
|
amt = 98;
|
|
res = coinChangeGreedy(coins3, 3, amt);
|
|
printf("\ncoins = ");
|
|
printArray(coins3, 3);
|
|
printf("amt = %d\n", amt);
|
|
printf("To collect %d, the minimum number of coins required is %d\n", amt, res);
|
|
printf("Actually, the minimum number required is 2, namely 49 + 49\n");
|
|
|
|
return 0;
|
|
}
|