DATA STRUCTURES PROGRAM • ARRAY TECHNIQUES
Find a Pair Sum with Two Pointers
Learn how to find a pair sum with two pointers using a clear C program.
PROBLEM UNDERSTANDING
Input and expected output
Sample input
No input required
Sample output
Pair = 2, 14
COMPLETE C PROGRAM
Complete C implementation
#include <stdio.h>
int main(void)
{
int values[] = {1, 2, 4, 6, 10, 14};
int target = 16, left = 0, right = 5;
while (left < right) {
int sum = values[left] + values[right];
if (sum == target) {
printf("Pair = %d, %d\n", values[left], values[right]);
return 0;
}
if (sum < target) left++;
else right--;
}
puts("No pair found.");
return 0;
}CURRENT STEP
SELECTED LINE
EXPECTED OUTPUT FOR THE SAMPLE
Pair = 2, 14
Step 0 of 0
PROGRAM EXPLANATION
Algorithm and explanation
- Read the required input values.
- Move the left pointer for a small sum and the right pointer for a large sum.
- Display the computed result.
Move the left pointer for a small sum and the right pointer for a large sum.
EFFICIENCY
Time and space complexity
Time complexity
O(n)
Auxiliary space
O(1)
DEBUGGING CHECKLIST
Common mistakes
Check this
Use the correct format specifier for every variable.
Check this
Initialize variables before using their values.
Check this
Check braces, semicolons and input order carefully.
Try it yourself
Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.
