6. Linear Search

🧸 ELI5: You lost your favorite toy car in a toy box full of 50 toys. You pick up toy #1, check if it's the car, put it down, pick up toy #2, check... You keep going until you find it. No shortcuts.

🌍 Real life: Scanning every song in an unsorted playlist looking for one title. Checking every locker in a hallway for your friend's name because lockers aren't sorted by name.

📝 Pseudocode:

function linearSearch(list, target):
    for i from 0 to length(list) - 1:
        if list[i] == target:
            return i
    return -1

🐹 Go:

package main

import "fmt"

func linearSearch(toys []string, target string) int {
	for i, toy := range toys {
		if toy == target {
			return i
		}
	}
	return -1
}

func main() {
	toys := []string{"ball", "robot", "car", "doll"}
	fmt.Println(linearSearch(toys, "car")) // 2
}

🇨 C:

#include <stdio.h>
#include <string.h>

int linear_search(const char *toys[], int n, const char *target) {
    for (int i = 0; i < n; i++) {
        if (strcmp(toys[i], target) == 0) return i;
    }
    return -1;
}

int main(void) {
    const char *toys[] = {"ball", "robot", "car", "doll"};
    printf("%d\n", linear_search(toys, 4, "car")); // 2
    return 0;
}

⏱️ Complexity: O(n) — worst case, you check every single toy.