Given two integers A and B where (A ? B). The task is to find K such that |A – K| = |B – K|. If no such K exists then print -1.
Examples:
Input: A = 2, B = 16
Output: 9
|2 – 9| = |16 – 9| = 7Input: A = 5, B = 2
Output: -1
Approach: It is given that A ? B. So let A < B then there are three cases:
- K < A: This gives A – K = B – K which gives A = B which is false.
- K > B: This gives K – A = K – B which is also false.
- A ? K ? B: This gives K – A = B – K which gives 2 * K = A + B
If A + B is odd, there is thus no solution. If A + B is even then the answer is (A + B) / 2.
Below is the implementation of the above approach:
C++
// C++ implementation of the approach#include <bits/stdc++.h>using namespace std;// Function to find k such that// |a - k| = |b - k|int find_k(int a, int b){ // If (a + b) is even if ((a + b) % 2 == 0) return ((a + b) / 2); return -1;}// Driver codeint main(){ int a = 2, b = 16; cout << find_k(a, b); return 0;} |
Java
// Java implementation of the approachclass GFG{ // Function to find k such that// |a - k| = |b - k|static int find_k(int a, int b){ // If (a + b) is even if ((a + b) % 2 == 0) return ((a + b) / 2); return -1;}// Driver codepublic static void main(String[] args){ int a = 2, b = 16; System.out.println(find_k(a, b));}}// This code is contributed by Code_Mech |
Python3
# Python3 implementation of the approach # Function to find k such that # |a - k| = |b - k| def find_k(a, b) : # If (a + b) is even if ((a + b) % 2 == 0) : return ((a + b) // 2); return -1; # Driver code if __name__ == "__main__" : a = 2; b = 16; print(find_k(a, b)); # This code is contributed by AnkitRai01 |
C#
// C# implementation of the approach using System;class GFG{ // Function to find k such that// |a - k| = |b - k|static int find_k(int a, int b){ // If (a + b) is even if ((a + b) % 2 == 0) return ((a + b) / 2); return -1;}// Driver codepublic static void Main(){ int a = 2, b = 16; Console.Write(find_k(a, b));}}// This code is contributed by chitranayal |
Javascript
<script>// Javascript implementation of the approach // Function to find k such that// |a - k| = |b - k|function find_k(a, b){ // If (a + b) is even if ((a + b) % 2 == 0) return ((a + b) / 2); return -1;}// Driver codevar a = 2, b = 16;document.write( find_k(a, b));// This code is contributed by akshitsaxenaa09</script> |
Output
9
Time Complexity: O(1)
Auxiliary Space: O(1)
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