rahulpadhy's blog

Segment tree
By rahulpadhy, history, 9 years ago, In English

Hi, I am new to segment trees. I am getting RE for this SPOJ question and I am unable to find out the mistake in my code. So, can you guys please help ?? Here's the link to the question... http://www.spoj.com/problems/GSS1/

And, here's my solution.. http://pastebin.com/dtKe4rx4

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9 years ago, # |
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Your logic is wrong.

Take this test:

3
2 -1 2
1
1 3

Your output: 4
Answer: 3

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    9 years ago, # ^ |
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    Answer should be 4 because we need to find the maximum possible sum obtained from the elements in the specified indices(2 + 2 = 4)... But my main concern is as to why I am getting RE for this question...

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      9 years ago, # ^ |
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      You can't do 2 + 2 because there's a -1 in between. Read the problem statement. They want maximum contiguous subarray sum. I solved it, I know what I'm talking about.

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      9 years ago, # ^ |
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      As for the runtime error, check out this test:

      3
2 -1 2
1
3 3

      You're not exiting the query function when your current range is completely outside the query range. You should do something like: 

      if (start > r || end < l)
     return 0;
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