原創

public class Test1 {
    public static void main(String[] args) {
        int[] nums = {1,2,4,6,9};
        int sum=20;
        int count=0;
        for(int a=0;a<20/nums[4]+1;a++){
            for(int b=0;b<20/nums[3]+1;b++){
                for(int c=0;c<20/nums[2]+1;c++){
                    for
 
(int d=0;d<20/nums[1]+1;d++){
                        for(int e=0;e<20/nums[0]+1;e++){
                            int sums=a*nums[4]+b*nums[3]+c*nums[2]+d*nums[1]+e*nums[0];
                            if(sums==sum){
                                if(e!=0)System.out.print(nums[0]+"*"+e);
                                if
 
(d!=0){
                                    if(e!=0)System.out.print("+");
                                    System.out.print(nums[1]+"*"+d);
                                }
                                if(c!=0){
                                    if(e!=0 ||d!=0)System.out.print("+");
                                    System
 
.out.print(nums[2]+"*"+c);
                                }
                                if(b!=0){
                                    if(e!=0 ||d!=0||c!=0)System.out.print("+");
                                    System.out.print(nums[3]+"*"+b);
                                }
                                if(a!=0){
                                    if(e!=0||d!=0||c!=0||b!=0)System.out.print("+");
                                    System.out.print(nums[4]+"*"+a);
                                }
                                System.out.println("="+sum);
                                count += 1;
                                continue;
                            }
                        }
                    }
                }
            }
        }
        System.out.println("共有"+count+"種情況。");
    }
}