19

Phase 4 - Level 5: Logical & Applied

Chapter 19 • Advanced

105 min

Phase 4 - Level 5: Logical & Applied

Introduction

This advanced level combines array operations with complex logic to solve real-world problems. You'll check array properties, find specific elements, and analyze patterns.

Key Concepts

Array Property Checks

  • Sorted Check: Is array sorted (ascending/descending)?
  • Uniqueness: Are all elements unique?
  • Range Check: Do elements fall in specific range?

Finding Specific Elements

  • Second Largest: Find second maximum
  • Second Smallest: Find second minimum
  • Range: Difference between max and min
  • Kth Element: Find element at specific position

Frequency Analysis

  • Frequency Array: Count occurrences of each element
  • Most Frequent: Element appearing most times
  • Elements Appearing More Than Once: Find duplicates

Applied Problems

  • Pairs with Sum: Find pairs summing to target
  • Elements Above Average: Count elements greater than average
  • Sum Excluding Extremes: Sum without max and min

Problem-Solving Approach

  1. Understand Requirement: What property or element needed?
  2. Plan Algorithm: Multiple passes or single pass?
  3. Handle Edge Cases: Empty, single element, all same
  4. Optimize: Can we solve in one pass?

Common Patterns

Two-Pass Approach

  • First pass: Find max/min
  • Second pass: Find second max/min

Single-Pass Approach

  • Track multiple values simultaneously
  • Update as you iterate

Frequency Counting

  • Use dictionary or nested loops
  • Count occurrences of each element

Hands-on Examples

Check if Array is Sorted

# Take array
n = int(input("Enter array size: "))
arr = []
for i in range(n):
    arr.append(int(input(f"Enter element {i+1}: ")))

# Check if sorted
is_sorted = True
for i in range(len(arr) - 1):
    if arr[i] > arr[i + 1]:
        is_sorted = False
        break

if is_sorted:
    print("Array is sorted in ascending order")
else:
    print("Array is not sorted")

Compare each element with next. If any element is greater than next, array is not sorted. If all comparisons pass, array is sorted.

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Phase 4 - Level 4: Aggregation & Comparison
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Phase 5 - Category 1: Basic String Handling

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