Find Missing Number on Array

// 代码是从eclipse直接copy过来的 请大家见谅 ，" 一个数组找到丢失的那个数 "
// BitSet的使用 https://www.cnblogs.com/xupengzhang/p/7966755.html


import java.util.Arrays; 

import java.util.BitSet; 

/**
 * 
 * @ClassName: FindMissingNums
 * @Description: find the numbers missing in Integer array 1 - 100
 * @author hepengyu
 * @date Sep 30, 2018 9:06:01 AM
 *
 */ public class FindMissingNums {
    public static void main(String[] args) {
        // one missing number        
  printMissageNums(new int [] { 1, 2, 3, 4, 6 }, 6);
        
        // duplicate number is OK //         printMissageNums(new int[] { 1, 2, 3, 4, 4, 5, 6 }, 8);         
        // only one missing number the second solution          

int[] array = new int[] {1,2,3,4,5,7,8,9,10};
        int missing = getMissingNumber(array, 10);
        
        System.out.printf("Missing number in array %s is %d %n",Arrays.toString(array),missing);
    }
    
    /**
     * 
     * @Title: printMissageNums 

* @Description: print the missing numbers in Integer Arrays 

* @param @param arrays 

* @param @param count the length of arrays 

* @return   void return type 

* @throws      

*/     

private static void printMissageNums(int[] arrays, int count) {
        // missing numbers         

int missingNum = count - arrays.length;
        BitSet bitSet = new BitSet(count);
        for (int array : arrays) {
            bitSet.set(array - 1);
        }
        System.out.printf("Missing numbers in integer array %s, with total number %d is %n", Arrays.toString(arrays), count);
        int lastMissingIndex = 0;
        for (int i = 0; i < missingNum; i++) {
            lastMissingIndex = bitSet.nextClearBit(lastMissingIndex);
            System.out.println(++lastMissingIndex);
        }
    }
    
    /**
     * 
     * @Title: getMissingNumber 
     * @Description: only one missing number
     * @param @param number
     * @param @param count
     * @param @return     

* @return int    return type 
     * @throws      */     private static int getMissingNumber(int[] number , int count) {
        int actualSum = 0;
        int expectedSum = count * (1 + count)/2;
        for(int array : number) {
            actualSum += array;
        }
        return expectedSum - actualSum;
    }
}