Coin Change
Given coin denominations and a target amount, return the fewest coins needed. Return -1 if not possible.
Example:
1,2,5 11
3
- The target amount is 11 and the available coin denominations are 1, 2, and 5.
- To find the fewest coins needed, we can use a combination of the largest denomination (5) and smaller denominations to reach the target amount: 5+5+1=11.
- This combination requires 3 coins, which is the fewest number of coins needed to reach the target amount.
- Therefore, the output is 3, indicating that 11 can be made with 3 coins.
Constraints:
- 1 <= len(coins) <= 12
- 1 <= coins[i] <= 2^31 - 1
- 0 <= amount <= 10^4
Background Knowledge
The Coin Change problem is a classic example of a Dynamic Programming problem. Dynamic Programming is a method for solving complex problems by breaking them down into simpler subproblems, solving each subproblem only once, and storing the results to avoid redundant computation. This approach is particularly useful for problems that have overlapping subproblems or optimal substructure, meaning that the problem can be broken down into smaller subproblems and the optimal solution to the larger problem can be constructed from the optimal solutions of the subproblems.
In the context of the Coin Change problem, we are given a set of coin denominations and a target amount, and we need to find the fewest coins needed to reach the target amount. This problem can be broken down into smaller subproblems, such as finding the fewest coins needed to reach a smaller amount, and the solutions to these subproblems can be used to construct the solution to the larger problem. The key concept here is to use a bottom-up approach, where we start with the smallest subproblems and build up to the larger problem, using the solutions to the smaller subproblems to inform the solution to the larger problem.
The Coin Change problem also involves the concept of minimization, where we need to find the minimum number of coins needed to reach the target amount. This is a common theme in Dynamic Programming problems, where we need to optimize a certain objective function, such as minimizing the number of coins or maximizing the value of a certain quantity. To solve this problem, we will need to use a combination of mathematical insights, such as the concept of minimum and maximum, and algorithmic techniques, such as iteration and recursion.
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