Minesweeper

If you are designing a minesweeper game, you would need to mark each block with how many mines are adjacent to it.

Write a program that places mines in a square grid. And marks each block with the number of mines adjacent to it.

Palindromes - Solution

There are multiple ways to solve this trivial problem.
For a beginner, there is one catch in this problem. How to make it case insensitive? Basically, we can do so by changing the string to all upper or all lowercase letters and then check for palindromes.

There maybe any number of ways to approach this problem. I'll list down the 2 ways that usually people apply.

1. Reverse the string and check if the strings are the same



There are quite a few things to learn here.
i> There are library functions available to check if a character is uppercase or lowercase. There are also functions to convert a character from uppercase to lowercase and visa-versa. You can find these functions is ctype.h header file.
ii> Note that we did not compare the reverse of the string with str using the '==' operator. Can you guess why? Basically, because the '==' operator returns true only if the two strings share the same memory location. So we use the 'compare' method in the 'string' class.


2. Compare the 1st against the last character, 2nd against the 2nd last character and so on till we reach the middle.
This one is simple. Here is the code.



Click on the images for code clarity.

Problem 9 - Palindromes

Write a program to find if a string is a palindrome.
Make it case insensitive.

Eg. "MADAM" - returns true
"ROB" - returns false
"Madam" - returns true
"mADaM" - returns true
"WhaWha"- returns false

Day 8 - Solution

The first way is to go by a Brute Force string matching technique.
I guess its useless to give the algorithm if you are giving the source code anyways.

So here is the program.



Now lets try to do the same using the built in features of the 'string' class. Remember, our strings are not (char *) any more, they are objects of the 'string' class. Check out how our whole function that we wrote above, is replaced with a single statement.

Prog:



Note: Click on the image for clarity in reading.

Day 8 - Substring

You are given two strings - haystack and needle.
You have to find the position of the first occurrence of needle in haystack.
Write a function that takes haystack and needle as input and returns the position of the first occurrence of needle or -1 if needle is not found in haystack.

Eg.

haystack = "Once upon a time, there lived a little boy named Jingle!"
needle = "up"
Return Value = 5

If needle = "fox"
Return Value = -1

Day 7 - Solution

In a hurry today.
Please see the code!



click on the image for clarity.

Day 7 - Who Won?

You are given an array of strings containing a 3 letter country name followed by a hyphen (-) and A 3 digit number. These strings represent the number of points earned by the students of the respective country in a programming competition.
NOTE: There are only 3 countries participating, India, China and USA. The 3 letter code for the countries are IND, CHI and USA respectively.

Write a function that calculates the total number of points scored by the students of IND, CHI and USA and returns a string in the same format with the country code followed by a hyphen followed by the total points scored by the country which has the highest points.

eg
INPUT -> ["IND-32","CHI-33","USA-29","USA-30","IND-12","CHI-34"]
OUTPUT -> "CHI-67"

NOTE: It is guaranteed that the sum of the scores won't be equal.