Given a number N, the task is to find the number of unique ways in which N can be represented as a sum of two positive integers.
Input: N = 7
(1 + 6), (2 + 5) and (3 + 4).
Input: N = 200
Approach: The number of ways in which the number can be expressed as the sum of two positive integers are 1 + (N – 1), 2 + (N – 2), …, (N – 1) + 1 and (N – 2) + 2. There are N – 1 terms in the series and they appear in identical pairs i.e. (X + Y, Y + X). So the required count will be N / 2.
Below is the implementation of the above approach:
- Write a program to reverse digits of a number
- Write an Efficient Method to Check if a Number is Multiple of 3
- Write an Efficient C Program to Reverse Bits of a Number
- Minimum number of jumps to reach end
- Multiply two integers without using multiplication, division and bitwise operators, and no loops
- Find minimum number to be divided to make a number a perfect square
- Find whether a given number is a power of 4 or not
- Print all combinations of points that can compose a given number
- Check if a number is multiple of 5 without using / and % operators
- Median in a stream of integers (running integers)
- Given a number, find the next smallest palindrome
- Count the number of possible triangles
- Select a random number from stream, with O(1) space
- Program to convert a given number to words
- Efficient program to print all prime factors of a given number
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