java-basics/java-programs/MissingNumber_01.java at master · Sethu1910/java-basics · GitHub

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package misc;

/**

* Logic:-

* 01. Find the sum of n number using formula n=n*(n+1)/2

* 02. Subtract (sum of n numbers – sum of elements present in the array).

public class MissingNumber_01 {

public static int missingNumber(int[] arr) {

int n = arr.length + 1;

int sum = n * (n + 1) / 2;

int restSum = 0;

for(int i = 0; i< arr.length; i++ ) {

restSum += arr[i];

}

int missingNumber = sum - restSum;

return missingNumber;

}

public static void main(String[] args) {

int[] arr = {1, 2, 3, 4, 6, 7, 8};

System.out.println("Missing Number: " +missingNumber(arr));

}

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