322. change exchange

Preface

C++ It's a high-level programming language , from C Language expansion and upgrading , As early as 1979 By Benjani · Strauss LUP is AT&T Developed by Bell studio .
C++ Both can be carried out C Process programming of language , It can also be used for object-based programming characterized by abstract data types , It can also carry out object-oriented programming characterized by inheritance and polymorphism .C++ Good at object-oriented programming at the same time , You can also do process based programming .
C++ Have the practical characteristics of computer operation , At the same time, it is also committed to improving the programming quality of large-scale programs and the problem description ability of programming languages .

Java Is an object-oriented programming language , Not only absorbed C++ The advantages of language , It's abandoned C++ The incomprehensible inheritance in 、 Concepts such as pointer , therefore Java Language has two characteristics: powerful and easy to use .Java As the representative of static object-oriented programming language , Excellent implementation of object-oriented theory , Allow programmers to do complex programming in an elegant way of thinking .
Java It's simple 、 object-oriented 、 Distributed 、 Robustness, 、 Security 、 Platform independence and portability 、 Multithreading 、 Dynamic and so on .Java Can write desktop applications 、Web Applications 、 Distributed system and embedded system applications, etc .

Python By Guido of the Dutch Society for mathematical and computer science research · Van rosum On 1990 It was designed in the early 's , As a course called ABC A substitute for language .Python Provides efficient advanced data structure , It's also a simple and effective way of object-oriented programming .Python Syntax and dynamic types , And the nature of interpretative language , Make it a programming language for scripting and rapid application development on most platforms , With the continuous update of the version and the addition of new language features , Gradually used for independent 、 Development of large projects .
Python The interpreter is easy to extend , have access to C Language or C++（ Or something else can be done through C Calling language ） Expand new functions and data types .Python It can also be used as an extensible programming language in customizable software .Python Rich library of standards , Provides source code or machine code for each major system platform .
2021 year 10 month , Compiler for language popularity index Tiobe take Python Crowned the most popular programming language ,20 Put it in... For the first time in years Java、C and JavaScript above .

describe

Give you an array of integers coins , Coins of different denominations ; And an integer amount , Represents the total amount .

Calculate and return the amount needed to make up the total amount The minimum number of coins . If no combination of coins can make up the total amount , return -1 .

You can think of the number of coins of each kind as infinite .

Example 1：

Input ：coins = [1, 2, 5], amount = 11
Output ：3
explain ：11 = 5 + 5 + 1

Example 2：

Input ：coins = [2], amount = 3
Output ：-1

Example 3：

Input ：coins = [1], amount = 0
Output ：0

public class Solution {
    public int coinChange(int[] coins, int amount) {
        if (amount < 1) {
            return 0;
        }
        return coinChange(coins, amount, new int[amount]);
    }

    private int coinChange(int[] coins, int rem, int[] count) {
        if (rem < 0) {
            return -1;
        }
        if (rem == 0) {
            return 0;
        }
        if (count[rem - 1] != 0) {
            return count[rem - 1];
        }
        int min = Integer.MAX_VALUE;
        for (int coin : coins) {
            int res = coinChange(coins, rem - coin, count);
            if (res >= 0 && res < min) {
                min = 1 + res;
            }
        }
        count[rem - 1] = (min == Integer.MAX_VALUE) ? -1 : min;
        return count[rem - 1];
    }
}