Linear Search in an Array of N Elements with Early Exit

Given an array Arr of N integers and a target Key, perform a sequential scan from index 0 to N-1. If Arr[i] == Key, record the index, set Found = 1, and immediately break early to eliminate redundant comparisons.

Step 1: Start.
Step 2: Read N.
Step 3: Read array elements Arr[0], Arr[1], ..., Arr[N-1].
Step 4: Read target Key.
Step 5: Set Found = 0, i = 0.
Step 6: While (i < N):
         If (Arr[i] == Key):
             Print 'Key found at position i'.
             Found = 1.
             Break loop (Go to Step 7).
         Else:
             i = i + 1.
Step 7: If (Found == 0):
         Print 'Key not present in array'.
Step 8: Stop.

         +-----------------+
         |     [ START ]   |
         +-----------------+
                  |
                  v
         +-----------------+
         |  Read N & Array |
         |     Read Key    |
         +-----------------+
                  |
                  v
         +-----------------+
         | Found=0, i=0    |
         +-----------------+
                  |
                  v
               /     \
             /   i < N ?   \ ---NO---> /       \
             \             /          / Found==0?\ ---YES--> [Print Not Found] --> [STOP]
                  | YES               \         /
                  v                        | NO
               /     \                     v
             /Arr[i]==Key?\                [STOP]
             \            /
            YES/        \NO
             v            v
      +--------------+  +-----------+
      | Set Found=1  |  | i = i + 1 |
      | Print pos i  |  +-----------+
      +--------------+        |
             |                +------> (Loop to i < N?)
             v
      [ EARLY EXIT ] --> [ STOP ]

Edit the code directly with the Edit Code button, provide custom inputs, and press Run Code to compile and execute in the live terminal console below!

#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n;
    cout << "Enter number of elements in array N: ";
    if (!(cin >> n) || n <= 0) {
        cout << "Invalid array size N!\n";
        return 1;
    }

    vector<int> arr(n);
    cout << "Enter " << n << " integers:\n";
    for (int i = 0; i < n; ++i) {
        cin >> arr[i];
    }

    int key;
    cout << "Enter target key to search: ";
    cin >> key;

    int foundIndex = -1;
    int comparisons = 0;

    // Linear search with early exit
    for (int i = 0; i < n; ++i) {
        comparisons++;
        if (arr[i] == key) {
            foundIndex = i;
            break; // Early exit break
        }
    }

    cout << "\n========================================\n";
    if (foundIndex != -1) {
        cout << "SUCCESS: Target key [" << key << "] FOUND at index " << foundIndex 
             << " (Position " << (foundIndex + 1) << " in array).\n";
        cout << "Comparisons executed : " << comparisons << " of " << n 
             << " (" << (n - comparisons) << " comparisons saved!)\n";
    } else {
        cout << "FAILURE: Target key [" << key << "] NOT FOUND in the array.\n";
        cout << "Comparisons executed : " << comparisons << " (Full scan completed).\n";
    }
    cout << "========================================\n";
    return 0;
}

Input:
5
15 23 7 42 9
7

Output:
========================================
SUCCESS: Target key [7] FOUND at index 2 (Position 3 in array).
Comparisons executed : 3 of 5 (2 comparisons saved!)
========================================