9.Fizz Buzz

Given number n. Print number from 1 to n. But:

when number is divided by 3, print "fizz".

when number is divided by 5, print "buzz".when number is divided by both 3 and 5, print "fizz buzz".Example

If n = 15, you should return:

[

"1", "2", "fizz", "4", "buzz", "fizz", "7", "8", "fizz", "buzz", "11", "fizz", "13", "14", "fizz buzz"]

Challenge

Can you do it with only one if statement?

看了一些答案使用了多个if,这里给出几种方案给大家参考下

1、建立HashMap,将3,6,9,12,5,10,0(i%15==0)所对应的字符串分别映射，这样一个if(map.containsKey(i%15))即可

public static HashMap
    
      map = new HashMap<>();     static{         map.put(3,"fizz");         map.put(6,"fizz");         map.put(9,"fizz");         map.put(12,"fizz");         map.put(5,"buzz");         map.put(10,"buzz");         map.put(0,"fizz buzz");     }    public List
     
       fizzBuzz(int n) {        List
      
        ret = new ArrayList<>();        for(int i=1;i<=n;i++){            int key = i%15;            if(map.containsKey(key)){                ret.add(map.get(key));            }else{                ret.add(""+i);            }        }        return ret;    }
      
     
    

2、对1进行优化，只映射3,5,8，这里需要一点数学技巧，大家看代码就理解了

public static HashMap
    
      map = new HashMap<>();     static{         map.put(3,"fizz");         map.put(5,"buzz");         map.put(8,"fizz buzz");     }    public List
     
       fizzBuzz(int n) {        List
      
        ret = new ArrayList<>();        for(int i=1;i<=n;i++){            int key = f(i,3)+f(i,5);            if(map.containsKey(key)){                ret.add(map.get(key));            }else{                ret.add(""+i);            }        }        return ret;    }        private int f(int i,int k){        return (k-i%k)*((k-i%k)/k);    }
      
     
    

3、利用&&的截断功能

public List
    
      fizzBuzz(int n) {          List
     
       ret = new ArrayList<>(n);            for(int i=1;i<=n;i++){                String str = null;                boolean bool1 = i%3==0&&(str="fizz")!=null;                boolean bool2 = i%5==0&&(str="buzz")!=null&& i%3==0&&(str="fizz buzz")!=null;                if(str==null){                    ret.add(""+i);                }else {                    ret.add(str);                }            }                       return ret;      }
     
    

暂时想到这些，欢迎指正