Download presentation

Presentation is loading. Please wait.

Published byAlanna Maslyn Modified over 4 years ago

1
Algorithm Design approaches Dr. Jey Veerasamy

2
Petrol cost minimization problem You need to go from S to T by car, spending the minimum for petrol. 2 ST

3
Quick-sort

4
Merge-sort

5
Divide & Conquer - characteristics

6
# of stops minimization problem Similar to petrol cost minimization problem, but we are minimizing # of stops. ST

7
Activity selection problem

8
Fractional knapsack problem Gold powder, silver powder, … Thief has limited weight capacity

9
Greedy approach - characteristics

10
10 Fibonacci number problem Definition of Fibonacci number: F(1) = 1 F(2) = 2 F(n) = F(n-1) + F(n-2), when n > 2 Recursive solution using D&C approach: int f(int n) { if (n == 1) return 1; else if (n == 2) return 2; else return f(n-1) + f(n-2); }

11
11 D&C Solution for F(6) F(1)F(2) F(3)F(2) F(4) F(3) F(5) F(2)F(1) F(6) F(1)F(2) F(3)F(2) F(4) Several subproblems are solved repeatedly - Not an efficient approach.

12
12 DP solution for F(6) F(1)F(2)F(3)F(4)F(5)F(6) DP uses a table and bottom-up approach (note that D&C used top-down approach): int fib(int n) { int f[n+1]; f[1] = 1; f[2] = 2; for (i=3 ; i<= n ; i++) f[i] = f[i-1]+f[i-2]; return f[n]; } Computations are NOT repeated!

13
Knapsack problem Individual pieces with specific weights, thief wants to know whether there is an exact match for his weight limit.

14
Dynamic programming - characteristics

Similar presentations

OK

Merge Sort: Taught By Example CO1406: Algorithms and Data Structures Module Lecturer: Dr. Nearchos Paspallis Week 10 Lab - Practice with Merge sort and.

Merge Sort: Taught By Example CO1406: Algorithms and Data Structures Module Lecturer: Dr. Nearchos Paspallis Week 10 Lab - Practice with Merge sort and.

© 2018 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google