AlgoStories

Algorithm Cheatsheets

Quick reference guides for algorithm patterns, implementation templates, and time complexity analysis.

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Sample: Two Pointers Cheatsheet

When to use:

  • Finding pairs in a sorted array
  • Removing duplicates from sorted arrays
  • Squaring a sorted array
  • Triplet problems (3Sum, 3Sum Closest)

Template:

function twoPointers(arr) {
  let left = 0;
  let right = arr.length - 1;
  
  while (left < right) {
    // Process the elements at left and right pointers
    
    // Move pointers based on condition
    if (condition) {
      left++;
    } else {
      right--;
    }
  }
  
  return result;
}

Time & Space Complexity:

Time Complexity:
O(n) for most applications
Space Complexity:
O(1) for in-place operations
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