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Data Structures
  • Data Structures Manual
  • Arrays
    • Array ADT
    • Linear Search
    • Binary Search
    • Some More Basic Operations
    • Reversing an Array
    • Operations in a Sorted Array
    • Merging Two Arrays
    • Set Operations
    • Finding Missing Elements
    • Duplicates in an Array
    • Getting a Pair whose Sum = K
    • Finding Max & Min in Single Scan
  • Strings
    • Finding the Length of a String
    • Changing Cases in a String
    • Finding Number of Vowels, Consonants & Words
    • Reversing a String
    • Checking for Palindrome
    • Duplicates in a String
    • Checking if Strings are Anagrams
    • Permutations of a String
  • Singly Linked List
    • Displaying the Nodes
    • Counting the Nodes
    • Sum of all Nodes
    • Finding the Maximum Element
    • Searching in a Node
    • Inserting a Node
    • Inserting a Node in Sorted List
    • Deleting a Node
    • Checking if List is Sorted
    • Removing Duplicates from a List
    • Reversing a Linked List
    • Concatenating Two Lists
    • Detecting a Loop in Linked List
    • Merge Two Sorted Lists
    • Finding the Middle Node
  • Cirular Linked List
    • Displaying the Nodes
    • Inserting a Node
    • Deleting a Node
  • Doubly Linked List
    • Inserting a Node
    • Deleting a Node
    • Reversing a Doubly Linked List
    • Circular Doubly Linked List
  • Stack
    • Stack Using Array
    • Stack Using Linked List
    • Balancing Parenthesis
    • Infix to Postfix
    • Evaluation of Postfix Expression
  • Queue
    • Queue using Array
    • Queue using Linked List
    • Double Ended Queue
  • Binary Tree
    • Creating a Binary Tree using Queue
    • Recursive Tree Traversals
    • Iterative Tree Traversals
    • Level Order Traversal
    • Counting Nodes in a Binary Tree
    • Finding the Height of Tree
    • Finding Sum of All Nodes
  • Binary Search Tree
    • Searching in a BST
    • Inserting in a BST
    • Deleting in a BST
  • AVL Tree
    • Inserting in an AVL Tree
    • AVL Tree Rotations
    • Deleting in an AVL Tree
  • Heap
    • Inserting in a Heap
    • Deleting in a Heap
    • Heapify
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  • For Sorted Arrays:
  • For Unsorted Arrays:

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  1. Arrays

Getting a Pair whose Sum = K

Obtaining a pair of elements in the array whose sum = k.

For Sorted Arrays:

void findPair(int a[], int n, int key) {

    // Set i to starting index and j to last index
    int i = 0, j = n-1;
    
    while (i < j) {
        // If pair is found, increment i and decrement j
        if (a[i] + a[j] == key) {
            printf("Pair : %d and %d\n", a[i], a[j]); 
            i++;
            j--;
        }
        // If sum is greater than key, decrement j
        else if (a[i] + a[j] > key) {
            j--;
        }
        // If sum is smaller than key, increment i
        else {
            i++;
        }
        
    }

}

For Unsorted Arrays:

void findPair(int a[], int n, int max, int key) {
    
    // Create and initialize hash array with 0
    int h[max];
    for (int i = 0; i < max; i++) {
        h[i] = 0;
    }
    
    for (int i = 0; i < n; i++) {
        // Check if the suitable pair is present
        if (h[key - a[i]] != 0) {
            printf("Pair : %d and %d\n", a[i], key-a[i]);
        } 
        h[a[i]]++;
    }

}

Contributed by Nitin Ranganath

PreviousDuplicates in an ArrayNextFinding Max & Min in Single Scan

Last updated 4 years ago

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