算法学习(一)位运算练习

谁践踏了优雅 2022-12-18 05:57 127阅读 0赞

## 位运算应用 ##

案例：输入一串数组并赋值，赋值的范围为1~arr.length-1，然后生成一个随机数(1 ~ arr.length-1),将生成的随机数放在arr\[arr.length-1\] ，生成一个随机位置，将数组最后一位和生成的随机位置所在的数组交换，最后找出重复的那个数组。

public class FindRepetition { 
    
        public static void main(String[] args) { 
            Scanner scanner = new Scanner(System.in);
            System.out.println("-------------请输入数组的长度------------");
            int N = scanner.nextInt()+1;
            int[] ints = new int[N];
            //solution01(ints);
            solution02(ints);
        }
    
    
        public  static  void solution01(int ints[]){ 
            int N = ints.length;
            for (int i = 0; i < ints.length-1; i++) { 
                ints[i]=i+1;
            }
            Random random = new Random();
            int ran = random.nextInt(ints.length - 1)+1;
            ints[ints.length-1]=ran;
            int index = new Random().nextInt(N);
            //需要交换
            changePositionByIndex(ints,index);
            print(ints,5);
            shuffleArr(ints);
            print(ints,5);
            int temp=0;
            for (int i = 0; i < ints.length; i++) { 
                temp = temp^ints[i];
                for (int j = 0; j < ints.length - 1; j++) { 
                    temp = temp ^ (j+1);
                }
            }
            System.out.println(temp);
        }
    
        public static  void solution02(int ints[]){ 
            System.out.println("----------------------");
            int N = ints.length;
            for (int i = 0; i < ints.length-1; i++) { 
                ints[i]=i+1;
            }
            Random random = new Random();
            int ran = random.nextInt(ints.length - 1)+1;
            ints[ints.length-1]=ran;
            int index = new Random().nextInt(N);
            //需要交换
            changePositionByIndex(ints,index);
            print(ints,6);
    
            int[] helper = new int[ints.length - 1];
            for (int i = 0; i < helper.length+1; i++) { 
                helper[ints[i]-1]++;
            }
            for (int i = 0; i < helper.length; i++) { 
                if(helper[i]==2){ 
                    System.out.println(ints[i]);
                }
            }
        }
    
        public  static  void  changePositionByIndex(int arr [] , int index){ 
            for (int i = 0; i < arr.length -1 ; i++) { 
                int temp =  arr[arr.length-1];
                arr[arr.length-1]=arr[index];
                arr[index]=temp;
            }
        }
        
        public  static  void print(int arr [],int columns){ 
    
            for (int i = 0; i < arr.length; i++) { 
                if(i==0 || i==arr.length-1){ 
                    if(i==0){ 
                        System.out.print("["+arr[i]+';');
                    }else { 
                        System.out.print(arr[i]+"]"+"\n");
                    }
                }else { 
                    if(i%columns == 0){ 
                        System.out.print("\n"+arr[i]+";");
                    }else { 
                        System.out.print(arr[i]+";");
                    }
                }
            }
        }
    
        public static void shuffleArr(int arr []){ 
            int len = arr.length;
    
            for(int i = 0;i < len; i++){ 
                int currentRandom = new Random().nextInt(len-1);
                int current = arr[i];
                arr[i] = arr[currentRandom];
                arr[currentRandom] = current;
            }
        }
    }

运行结果:  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3h1ZXNoYW5mZWl0aWFu_size_16_color_FFFFFF_t_70_pic_center]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3h1ZXNoYW5mZWl0aWFu_size_16_color_FFFFFF_t_70_pic_center]: /images/20221122/c69387d349ba41ffa936aaac7a4a2769.png