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
1andxinclusively equals the sum of all elements betweenxandninclusively.
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
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