Java Hyd Team

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How do you find the missing number in a given integer array of 1 to 100?

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;
}

}

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47 views11:49