给定一个 1-100 的整数数组，请找到其中缺少的数字。

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

import java.util.Arrays; import java.util.BitSet;   /**  * Java program to find missing elements in a Integer array containing numbers  * from 1 to 100.  *  */ public class MissingNumberInArray {       public static void main(String args[]) {           // one missing number         printMissingNumber(new int[] { 1, 2, 3, 4, 6 }, 6);           // two missing number         printMissingNumber(new int[] { 1, 2, 3, 4, 6, 7, 9, 8, 10 }, 10);           // three missing number         printMissingNumber(new int[] { 1, 2, 3, 4, 6, 9, 8 }, 10);           // four missing number         printMissingNumber(new int[] { 1, 2, 3, 4, 9, 8 }, 10);           // Only one missing number in array         int[] iArray = new int[] { 1, 2, 3, 5 };         int missing = getMissingNumber(iArray, 5);         System.out.printf("Missing number in array %s is %d %n", Arrays.toString(iArray), missing);     }       /**      * A general method to find missing values from an integer array in Java. This      * method will work even if array has more than one missing element.      */     private static void printMissingNumber(int[] numbers, int count) {         int missingCount = count - numbers.length;         BitSet bitSet = new BitSet(count);           for (int number : numbers) {             bitSet.set(number - 1);         }           System.out.printf("Missing numbers in integer array %s, with total number %d is %n", Arrays.toString(numbers),                 count);         int lastMissingIndex = 0;           for (int i = 0; i < missingCount; i++) {             lastMissingIndex = bitSet.nextClearBit(lastMissingIndex);             System.out.println(++lastMissingIndex);         }       }       /**      * Java method to find missing number in array of size n containing numbers from      * 1 to n only. can be used to find missing elements on integer array of numbers      * from 1 to 100 or 1 - 1000      */     private static int getMissingNumber(int[] numbers, int totalCount) {         int expectedSum = totalCount * ((totalCount + 1) / 2);         int actualSum = 0;         for (int i : numbers) {             actualSum += i;         }           return expectedSum - actualSum;     }   }