DSAArraysStrings

Arrays and Strings: The Foundation

Deep dive into array and string manipulation techniques every developer should know.

January 18, 20245 min read

Arrays and Strings: The Foundation

Arrays and strings are the most fundamental data structures. Mastering them is essential for technical interviews and everyday programming.

Array Fundamentals

Key Operations

Access: O(1)
Search: O(n)
Insert at end: O(1) amortized
Insert at index: O(n)

Common Patterns

Two Pointers

function isPalindrome(s) {
  let left = 0, right = s.length - 1;
  while (left < right) {
    if (s[left] !== s[right]) return false;
    left++;
    right--;
  }
  return true;
}

Sliding Window

function maxSum(arr, k) {
  let sum = 0;
  for (let i = 0; i < k; i++) sum += arr[i];
  
  let maxSum = sum;
  for (let i = k; i < arr.length; i++) {
    sum = sum - arr[i - k] + arr[i];
    maxSum = Math.max(maxSum, sum);
  }
  return maxSum;
}

String Manipulation

Essential Methods

const s = "hello world";
s.split(' ');        // ['hello', 'world']
s.substring(0, 5);   // 'hello'
s.includes('world'); // true
s.indexOf('o');      // 4

Practice Problems

Reverse a string in-place
Find all anagrams in a string
Longest substring without repeating characters

Master these patterns and you'll handle 80% of array/string problems.

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