Find Middle Point of Segment from Given Lengths in C++

In this problem, we are given an array arr[] of size m representing the lengths of line segments.

The line segments are from 0 to arr[0] , arr[0] to arr[1] and so on. Our task is to find the segment which is at the middle of all segments.

Let’s take an example to understand the problem,

Input

arr[] = {5, 7, 13}

Output

3

Explanation

Segments are : (0, 5) , (5, 12), (12, 25)

Solution Approach

To solve the problem, we will find the middle point of the line by (arrSum/2). If this middle point is a starting or ending point of a line segment then print -1. Else, print the segment number.

Program to illustrate the working of our solution,

Example

 Live Demo

#include <iostream>
using namespace std;
int findSegmentWithMidPoint(int n, int m, int segment_length[]) {
   double centerPoint = (1.0 * n) / 2.0;
   int sum = 0;
   int segment = 0;
   for (int i = 0; i < m; i++) {
      sum += segment_length[i];
      if ((double)sum == centerPoint) {
         segment = -1;
         break;
      }
      if (sum > centerPoint) {
         segment = i + 1;
         break;
      }
   }
   return segment;
}
int main() {
   int m = 3;
   int segment_length[] = { 5, 7, 13 };
   int arrSum = segment_length[0];
   for(int i = 0; i < m; i++)
      arrSum += segment_length[i];
   int ans = findSegmentWithMidPoint(arrSum, m, segment_length);
   cout<<"The segment number where middle point lies is "<<ans;
   return 0;
}

Output

The segment number where middle point lies is 3