题解 | 硬币凑钱

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            System.out.println(check(a));
        }
    }

    public static int check(int num) {
        int [] coins = new int[num + 1];
        coins[1] = 1;

        for (int i = 2; i <= num; i++) {
            int a = 0, b = 0, c = 0;
            if (i > 1) {
                a = coins[i - 1] + 1;
            }
            if (i > 5) {
                b = coins[i - 5] + 1;
            } else if (i == 5) {
                b = 1;
            } else {
                b = a + 1;
            }
            if (i > 7) {
                c = coins[i - 7] + 1;
            } else if (i == 7) {
                c = 1;
            } else {
                c = a + 1;
            }
            coins[i] = min(a, b, c);
        }

        return coins[num];
    }

    public static int min(int a, int b, int c) {
        if (a - b > 0) {
            if (b - c > 0) {
                return c;
            } else {
                return b;
            }
        } else if (a - c > 0) {
            return c;
        } else {
            return a;
        }
    }

}