Facebook | Phone screen | Exclusive Time of Functions
guptapraveen2
69
MetaInterview

Date: 18/12/2018
Location: Seattle, USA

Initial facebook interview was set up for 45 min and an interviewer asked a single programming question.

Question: https://leetcode.com/problems/exclusive-time-of-functions

/*
Function  stage(start/ends)  time(start/end)
main    start     0
<----------- main running
foo     start      3
foo     end       7
<----------- main running
zoo     start    10
zoo     end     13
<-------------- main running
moo     start    15
foo     start     17
foo     end      18
<---------------- moo running
moo     end    20
< --------------main running
main    end    22

Consolidate time for each function.
*/
My Solution 
	class LogInfo
	{
		String functionName;
		String timeType;
		int time;


		LogInfo(String functionName, String timeType, int time)
		{
			this.functionName = functionName;
			this.timeType = timeType;
			this.time = time;
		}
	}

	class LogOfStack
	{
		String functionName;
		int startime;
		int totalTime;


		LogOfStack(String functionName, int startime, int totalTime)
		{
			this.functionName = functionName;
			this.startime = startime;
			this.totalTime = totalTime;
		}
	}


	public Map<String, Integer> consolidation(List<LogInfo> logInfos)
	{
		final Map<String, Integer> map = new HashMap<>();
		final Stack<LogOfStack> activeStack = new Stack<>();
		for (final LogInfo info : logInfos)
		{
			if (info.timeType.equals("start"))
			{
				if (!activeStack.isEmpty())
				{
					final LogOfStack previous = activeStack.peek();
					previous.totalTime = previous.totalTime + info.time - previous.startime;
					previous.startime = info.time;
				}

				activeStack.push(new LogOfStack(info.functionName, info.time, 0));
			}
			else
			{
				LogOfStack previous = activeStack.pop();
				previous.totalTime = previous.totalTime + info.time - previous.startime;
				if (!map.containsKey(info.functionName))
				{
					map.put(info.functionName, 0);
				}

				final int time = map.get(info.functionName) + previous.totalTime;
				map.put(info.functionName, time);

				if (!activeStack.isEmpty())
				{
					previous = activeStack.peek();
					previous.startime = info.time;
				}
			}
		}

		return map;
	}


	public static void main(String[] arg)
	{
		Facebook facebook = new Facebook();
		String main = "main";
		String foo = "foo";
		String zoo = "zoo";
		String moo = "moo";
		String pee = "pee";
		List<LogInfo> logInfos = new ArrayList<>();
		logInfos.add(facebook.new LogInfo(main, "start", 0));
		logInfos.add(facebook.new LogInfo(foo, "start", 3));
		logInfos.add(facebook.new LogInfo(foo, "end", 7));
		logInfos.add(facebook.new LogInfo(zoo, "start", 10));
		logInfos.add(facebook.new LogInfo(zoo, "end", 13));
		logInfos.add(facebook.new LogInfo(moo, "start", 15));
		logInfos.add(facebook.new LogInfo(foo, "start", 16));
		logInfos.add(facebook.new LogInfo(pee, "start", 17));
		logInfos.add(facebook.new LogInfo(pee, "end", 18));
		logInfos.add(facebook.new LogInfo(foo, "end", 18));
		logInfos.add(facebook.new LogInfo(moo, "end", 20));
		logInfos.add(facebook.new LogInfo(main, "end", 22));

		System.out.println(facebook.consolidation(logInfos));

	}

}
</details>
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