readme update, odd-even-jump.py

Author: Chris Wu

README.md

@@ -8,16 +8,24 @@ https://github.com/wuduhren/leetcode-python
 
 3. The question is at `https://leetcode.com/problems/the-file-name/`. For example, `merge-sorted-array.py`'s question is at `https://leetcode.com/problems/merge-sorted-array/`.
 
-# Really Great Resources
+# Resources
+These are the interview resources I personally used and only if it is really helpful I will put it here.
 ## System Design
+More resource  
 <https://github.com/shashank88/system_design>
+Architecture 101  
+<https://engineering.videoblocks.com/web-architecture-101-a3224e126947>
+How to scale up? There are also lots of tech interview related topic in his channel.  
+<https://www.youtube.com/watch?v=yPF94QiI2qk&t=385s>
 
 ## Data Structure and Algorithm
 Basic data structure and algorithm online course taught in Python. This course is design to help you find job and do well in the interview.  
 <https://classroom.udacity.com/courses/ud513>
 
-## Architecture 101
-<https://engineering.videoblocks.com/web-architecture-101-a3224e126947>
+##How to Prepare in a Structured Way
+<https://www.quora.com/How-should-I-prepare-for-my-Google-interview-if-I-have-1-month-left-and-I%E2%80%99m-applying-for-a-software-engineer-role/answer/Anthony-D-Mays?ch=10&share=5c488000&srid=W0jqp>
+<https://www.quora.com/How-can-I-get-a-job-at-Facebook-or-Google-in-6-months-I-need-a-concise-work-plan-to-build-a-good-enough-skill-set-Should-I-join-some-other-start-up-or-build-my-own-projects-start-up-Should-I-just-focus-on-practicing-data-structures-and-algorithms/answer/Jimmy-Saade>
+<https://www.quora.com/What-should-I-know-from-the-CLRS-3rd-edition-book-if-my-aim-is-to-get-into-Google/answer/Jimmy-Saade>
 
 ## Overall Mindset
 This is a speech from Sean Lee on "How to Get a Job at the Big 4". I highly recommend this because it gives me the right mindset on how to put in the work.  
@@ -26,10 +34,6 @@ This is a speech from Sean Lee on "How to Get a Job at the Big 4". I highly reco
 CS DoJo on "How I Got a Job at Google as a Software Engineer". There are also lots of technique on coding interview in his channel.  
 <https://www.youtube.com/watch?v=UPO-9iMjBpc>
 
-## How to scale up
-There are also lots of tech interview related topic in his channel.  
-<https://www.youtube.com/watch?v=yPF94QiI2qk&t=385s>
-
 ## Interview Question Survey
 <https://www.glassdoor.com/index.htm>  
 <https://www.careercup.com/>

odd-even-jump.py

@@ -0,0 +1,86 @@
+class Solution(object):
+    def oddEvenJumps(self, A):
+    	l = len(A)
+        odd_jump = [-1]*l #odd_jump[i], when odd jump from index i, what index it is going to land
+        even_jump = [-1]*l #even_jump[i], when even jump from index i, what index it is going to land
+
+        odd = [False]*l #odd[i], can index i, starting by odd jump, go to the end
+        even = [False]*l #even[i], can index i, starting by even jump, go to the end
+        odd[-1] = True
+        even[-1] = True
+
+        #construct odd_jump
+        stack = []
+        for n, i in sorted((n, i) for i, n in enumerate(A)):
+        	while stack and stack[-1]<i:
+        		odd_jump[stack.pop()] = i
+        	stack.append(i)
+
+        #construct even_jump
+        stack = []
+        for n, i in sorted((-n, i) for i, n in enumerate(A)):
+        	while stack and stack[-1]<i:
+        		even_jump[stack.pop()] = i
+        	stack.append(i)
+
+        for i in reversed(xrange(l-1)):
+        	if odd_jump[i]!=-1:
+	        	odd[i] = even[odd_jump[i]]
+	        if even_jump[i]!=-1:
+	        	even[i] = odd[even_jump[i]]
+
+        return sum(odd)
+
+# Naive Approach
+class Solution(object):
+    def oddEvenJumps(self, A):
+    	def jump(start, odd):
+    		curr = None
+
+    		if odd:
+    			temp.add(start)
+
+    			n = float('inf')
+    			for i in xrange(start+1, len(A)):
+    				val = A[i]
+    				if i not in visited and val>=A[start] and val<n:
+    					n = val
+    					curr = i
+    		else:
+    			n = float('-inf')
+    			for i in xrange(start+1, len(A)):
+    				val = A[i]
+    				if i not in visited and val<=A[start] and val>n:
+    					n = val
+    					curr = i
+    		return curr
+
+        opt = set()
+        not_opt = set()
+        end = len(A)-1
+
+        for i in xrange(len(A)):
+        	if i in opt or i in not_opt: continue
+
+        	odd = True
+        	curr = i
+        	temp = set()
+        	visited = set()
+
+        	temp.add(i)
+
+        	while True:
+        		print curr
+        		visited.add(i)
+        		if curr==None:
+        			not_opt.update(temp)
+        			break
+        		if curr==end:
+        			opt.update(temp)
+        			break
+
+        		curr = jump(curr, odd)
+    			odd = not odd
+
+    	return len(opt)
+