c programming

1. CORE PROBLEM-
SOLVING STRATEGIES
Logic, Algorithms, Flowcharts & Examples

2. What is Problem Solving?
•Problem solving is identifying a
problem, planning a solution,
implementing it, and testing it.
•In programming, it involves:
• Understanding the problem
• Designing an algorithm
• Writing code
• Testing & refining

3. Why Problem-Solving Skills Matter
•They make you efficient and logical
• Help in debugging & optimization
• Build transferable skills across
domains
• Essential for competitive
programming & interviews

4. Understanding the Problem
• Define inputs, outputs, and constraints
before solving.
• Example: Find average of three numbers.

5. Understanding the Problem - Real-World Example
•A scenario where understanding the
problem is applied in daily life.
•• Practical situation
•• Outcome after applying strategy

6. Understanding the Problem - Programming Example
•Sample problem statement:
•• Algorithm steps
•• Possible code snippet
•• Output demonstration

7. Decomposition
•Break a big problem into smaller sub-
problems.
•Example: Sorting → input, compare,
swap, output.

8. Decomposition - Real-World Example
•A scenario where decomposition is
applied in daily life.
•• Practical situation
•• Outcome after applying strategy

9. Decomposition - Programming Example
•Sample problem statement:
•• Algorithm steps
•• Possible code snippet
•• Output demonstration

10. Pattern Recognition
•Identify similarities to problems solved
before.
•Example: Fibonacci → n = n-1 + n-2.

11. Pattern Recognition - Real-World Example
•A scenario where pattern
recognition is applied in daily life.
•• Practical situation
•• Outcome after applying strategy

12. Pattern Recognition - Programming Example
• Sample problem statement:
• • Algorithm steps
• • Possible code snippet
• • Output demonstration

13. Working Backwards
•Start from the goal and trace steps to
the start.
•Example: Find starting amount if final
is 200 after doubling 3 times.
₹

14. Working Backwards - Real-World Example
•A scenario where working backwards
is applied in daily life.
•• Practical situation
•• Outcome after applying strategy

15. Working Backwards - Programming Example
•Sample problem statement:
•• Algorithm steps
•• Possible code snippet
•• Output demonstration

16. Trial and Error
•Test multiple approaches until one
works.
•Example: Guessing a combination
lock.

17. Trial and Error - Real-World Example
• A scenario where trial and error is applied in daily life.
• • Practical situation
• • Outcome after applying strategy

18. Trial and Error - Programming Example
• Sample problem statement:
• • Algorithm steps
• • Possible code snippet
• • Output demonstration

19. Algorithmic Thinking
•Write step-by-step logical instructions.
•Example: Check if a number is prime.

20. Algorithmic Thinking - Real-World Example
• A scenario where algorithmic thinking is applied in daily life.
• • Practical situation
• • Outcome after applying strategy

21. Algorithmic Thinking - Programming Example
• Sample problem statement:
• • Algorithm steps
• • Possible code snippet
• • Output demonstration

22. Use of Models/Flowcharts
•Represent the process visually.
•Example: Cinema ticket booking
steps.

23. Use of Models/Flowcharts - Real-World Example
• A scenario where use of models/flowcharts is applied in daily life.
• • Practical situation
• • Outcome after applying strategy

24. Use of Models/Flowcharts - Programming Example
• Sample problem statement:
• • Algorithm steps
• • Possible code snippet
• • Output demonstration

25. Abstraction
•Ignore irrelevant details, focus on
essentials.
•Example: ATM withdrawal focuses on
PIN and amount.

26. Abstraction - Real-World Example
• A scenario where abstraction is applied in daily life.
• • Practical situation
• • Outcome after applying strategy

27. Abstraction - Programming Example
• Sample problem statement:
• • Algorithm steps
• • Possible code snippet
• • Output demonstration

28. Divide and Conquer
•Split into parts, solve each, then
combine.
•Example: Binary search in a sorted
list.

29. Divide and Conquer - Real-World Example
• A scenario where divide and conquer is applied in daily life.
• • Practical situation
• • Outcome after applying strategy

30. Divide and Conquer - Programming Example
• Sample problem statement:
• • Algorithm steps
• • Possible code snippet
• • Output demonstration

31. Optimization
•Improve an existing solution for
efficiency.
•Example: Find largest number with
fewer comparisons.

32. Optimization - Real-World Example
• A scenario where optimization is applied in daily life.
• • Practical situation
• • Outcome after applying strategy

33. Optimization - Programming Example
• Sample problem statement:
• • Algorithm steps
• • Possible code snippet
• • Output demonstration

34. Worked Example: Even/Odd Check
• Problem: Check if a number is even or odd.
• Inputs: Number n
• Outputs: 'Even' or 'Odd'
• Algorithm:
• 1. Start
• 2. Read n
• 3. If n % 2 == 0 → Even else Odd
• 4. Stop

35. Flowchart for Even/Odd
• Start → Input n → Decision (n % 2 == 0?)
• Yes → Even → Stop
• No → Odd → Stop

36. C Code for Even/Odd
•#include <stdio.h>
•int main() {
• int n; printf("Enter number: ");
• scanf("%d", &n);
• if (n % 2 == 0) printf("Even");
• else printf("Odd");
• return 0; }

37. Summary of Strategies
•
• Understanding the Problem → Define clearly
• • Decomposition → Break down tasks
• • Pattern Recognition → Use past knowledge
• • Working Backwards → Reverse approach
• • Trial and Error → Test multiple ways
• • Algorithmic Thinking → Stepwise plan
• • Use of Models/Flowcharts → Visual clarity
• • Abstraction → Focus on essentials
• • Divide and Conquer → Solve in parts
• • Optimization → Make it efficient

38. Practice Questions
•1. Find factorial of a number
•2. Check if a string is palindrome
•3. Search an element in a sorted list
•4. Optimize bubble sort
•5. Convert Celsius to Fahrenheit
•6. ATM cash withdrawal simulation

39. Find Factorial of a Number
•Algorithm:
•1. Start
•2. Read n
•3. fact = 1
•4. Repeat fact = fact * i for i=1 to n
•5. Print fact
•6. Stop

40. Find Factorial of a Number - Flowchart
•Flowchart: Start → Input n → Loop
i=1 to n → fact=fact*i → End loop
→ Output fact → Stop

41. Find Factorial of a Number - C Code
• #include <stdio.h>
• int main()
• {
• int n,i; long fact=1;
• scanf("%d", &n);
• for(i=1;i<=n;i++)
• fact*=i;
• printf("%ld",fact);
• return 0;
• }

42. Check if a String is Palindrome
•Algorithm:
•1. Start
•2. Read string
•3. Compare first and last characters
•4. If all match → Palindrome else Not
•5. Stop

43. Check if a String is Palindrome - Flowchart
•Flowchart: Start → Input string →
Compare chars → Decision → Output
result → Stop

44. Check if a String is Palindrome - C Code
• #include <stdio.h>
• #include <string.h>
• int main()
• {
• char str[100]; int i,flag=0; gets(str);
for(i=0;i<strlen(str)/2;i++)
• if(str[i]!=str[strlen(str)-i-1])
• flag=1; if(flag==0)
• printf("Palindrome");
• else printf("Not"); return
• 0;}

45. Key Takeaways
• • Apply the right strategy for the problem type
• • Always write algorithms before coding
• • Test with edge cases
• • Refine for efficiency
• • Practice regularly