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Fun one.. the punch line of this problem is quite common in Bit related problems on HackerRank - visualize it in your mind, and you will find: all bit 阅读全文
posted @ 2017-01-06 12:19
Tonix
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My first reaction is to have an unlimited length of bit-array, to mark existence. But if no extra mem is allowed, we can simply use 'sign' on each ind 阅读全文
posted @ 2017-01-06 08:31
Tonix
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The follow-up question is fun: "Could you do it in one-pass, using only O(1) extra memory and without modifying the value of the board?" When we meet 阅读全文
posted @ 2017-01-06 07:11
Tonix
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Increasing all elements by 1 except one element, equals to decreasing that one element. 阅读全文
posted @ 2016-11-12 11:57
Tonix
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Straight-forward strategy.. please take care of all details - data type, assignment order etc. 阅读全文
posted @ 2016-11-05 13:23
Tonix
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A simple math.. take care of data overflow though. 阅读全文
posted @ 2016-10-31 10:55
Tonix
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There are 3 possible approaches: DP, divide&conquer and greedy. And apparently, DP has O(n^2) complexity (TLE), DivideConquer can only be worse. Greed 阅读全文
posted @ 2016-10-24 03:25
Tonix
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A bit Greedy can achieve O(m) - the mid station between 2 adjacent cities has the longest distance within that range. 阅读全文
posted @ 2016-08-07 13:53
Tonix
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A simple math on modular calculations.Code below can be simplified of course. 阅读全文
posted @ 2016-07-24 07:56
Tonix
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Another interesting DP. Lesson learnt: how you define state is crucial.. 1. if DP[i] is defined as, longest wiggle(up\down) subseq AT number i, you wi 阅读全文
posted @ 2016-07-24 07:31
Tonix
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DP or Greedy - they are all in O(n) In editorial, a beautiful Greedy solution is given: "To reach the last cloud in a minimum number of steps, always 阅读全文
posted @ 2016-07-21 09:31
Tonix
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Another fun Greedy problem to work on: we simply go from first to second last person, as long someone is odd, we distribute bread to her and her next. 阅读全文
posted @ 2016-07-13 07:42
Tonix
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Greedy - though simple, but fun! 阅读全文
posted @ 2016-07-13 07:17
Tonix
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Fun with bits - carries etc. 阅读全文
posted @ 2016-07-07 07:59
Tonix
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I use a stack. Of course you can simply trace nodes with 9s - https://leetcode.com/discuss/111127/iterative-two-pointers-with-dummy-node-java-o-n-time 阅读全文
posted @ 2016-06-30 01:53
Tonix
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A mix of hashmap, list and heap. struct Tw { Tw(long long pts, int tid) { ts = pts; tweetid = tid; } long long ts; int tweetid; }; struct Cmp { bool o 阅读全文
posted @ 2016-06-28 01:56
Tonix
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Hits come and go - so we use queue. Nothing special. 阅读全文
posted @ 2016-06-28 01:03
Tonix
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Very nice DP problem. The key fact of a mutual-divisible subset: if a new number n, is divisible with the largest number m within a mutual-divisible s 阅读全文
posted @ 2016-06-27 13:20
Tonix
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Typical DFS problem. Simply get higher height and push_back. 阅读全文
posted @ 2016-06-27 11:35
Tonix
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Typical binary search.. but take care of data overflow if you are using C++ 阅读全文
posted @ 2016-06-27 11:21
Tonix
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