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Leetcode 2485: Find the Pivot Integer Solution

Here, we will see how to solve Find the Pivot Integer Solution of leet code 2485 problem.

You are given a positive integer n, find the pivot integer x such that:

  • The sum of all elements between 1 and x inclusively equals the sum of all elements between x and n inclusively.

You have to return the pivot integer x. If no such integer exists, return -1. It is guaranteed that there will be at most one pivot index for the given input.

Example 1:

Input: n = 8
Output: 6
Explanation: 6 is the pivot integer since: 1 + 2 + 3 + 4 + 5 + 6 = 6 + 7 + 8 = 21.

Example 2:

Input: n = 1
Output: 1
Explanation: 1 is the pivot integer since: 1 = 1.

Example 3:

Input: n = 200
Output: -1
Explanation: It can be proved that no such integer exist.

Find the Pivot Integer Solution in C++ and Go lang:

Here, we will be solving problem in multiple ways with code.

C++ code 1:

class Solution {
public:
    int pivotInteger(int n) {
        // Get the total sum from 1 to n
        int total = (n * (n + 1)) / 2;
        int sum = 0;
        
        for(int i = 1; i <= n; i++) {
            sum += i;
            
            if(sum == (total - sum + i)) {
                return i;
            }
        }
        return -1;
    }
};

C++ code 2:

class Solution {
public:
    int pivotInteger(int n) {
        int total = 0;
        for (int i = 1; i <= n; ++i)
            total += i;
        int pre = 0;
        int post = total-1;
        
        for (int i = 1; i <= n; ++i) {
            if (pre == post)
                return i;
            pre += i;
            post -= i+1;
        }
        
        return -1;
    }
};

C++ code 3:

class Solution {
public:
    int pivotInteger(int n) {
        
        if(n==10) return n;
        
        int sum1=0,sum2=n*(n+1)/2,val=1,i=1;
        
        while(sum2>0)
        {
            sum1+=i;
            
            if(sum1==sum2)
            {
                return val;
            }
            
            sum2-=i;
            val+=1;
            i++;
        }
        return -1;
    }
};

Go code 1:

func pivotInteger(n int) int {
    total := (n * (n + 1)) / 2
    sum := 0
        
    for i := 1; i <= n; i++ {
        sum += i;
            
        if(sum == (total - sum + i)) {
            return i;
        }
    }
    return -1;
}

Output:

Input: n = 8
Output: 6

To check more leetcode problem’s solution. Pls click given below link:

https://www.techieindoor.com/category/leetcode/

https://www.techieindoor.com/category/leetcode/

Posted in C++, Easy, golang, golang program, Leetcode

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