added BigO-notation.txt

BigO-notation.txt

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+## **Step One: Simplifying Expressions**
+
+Simplify the following big O expressions as much as possible:
+
+1. O(n + 10) => O(n)
+
+2. O(100 * n) => O(n)
+
+3. O(25) => O(1)
+
+4. O(n^2 + n^3) => O(n^3)
+
+5. O(n + n + n + n) => O(n)
+
+6. O(1000 * log(n) + n) => O(log(n)) ***O(n)
+
+7. O(1000 * n * log(n) + n) => O(n * log(n))
+
+8. O(2^n + n^2) => O(2^n)
+
+9. O(5 + 3 + 1) => O(1)
+
+10. O(n + n^(1/2) + n^2 + n * log(n)^10) 
+	=> O(n * log(n)^10) ***O(n^2)
+
+
+## **Step Two: Calculating Time Complexity**
+
+1. O(n)
+
+2. O(n)
+
+3. O(1)
+
+4. O(n^2) ***O(n)
+
+5. O(n^2)
+
+6. O(n)
+
+
+
+## **Part 3 - short answer**
+
+Answer the following questions
+
+1. True or false: n^2 + n is O(n^2). 
+	True
+2. True or false: n^2 * n is O(n^3). 
+	True
+3. True or false: n^2 + n is O(n). 
+	False
+4. What’s the time complexity of the .indexOf array method? 
+	O(n)
+5. What’s the time complexity of the .includes array method? 
+	O(n)
+6. What’s the time complexity of the .forEach array method? 
+	O(n)
+7. What’s the time complexity of the .sort array method? 
+	O(n log(n))
+8. What’s the time complexity of the .unshift array method? 
+	O(n)
+9. What’s the time complexity of the .push array method? 
+	O(1)
+10. What’s the time complexity of the .splice array method? 
+	O(n)
+11. What’s the time complexity of the .pop array method? 
+	O(1)
+12. What’s the time complexity of the Object.keys() function? 
+	O(n)
+Bonus. What’s the space complexity of the Object.keys() function? 
+	O(n)