25 Reverse Nodes in k-Group
Intuition & AlgorithmThe very intuitive method to solve this problem is:
splice the List into k nodes a group
reverse the group list
reconnect gr
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24 Swap Nodes in Pairs
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LeetCode
Intuition & Algorithm
Question 25 is a more general question of this one.
Suppose there are three pairs $p_0$, $p_1$ and $p_2$. We need to swap n
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377 Combination Sum IV
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Intuition & AlgorithmAt the first glampse of this question, I write down the dfs algorithm immediately. It works of course, but will encounter the
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216 Combination Sum III
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LeetCode
Intuition & AlgorithmNumbers 1-9 can be seen as candidates in the previous questions, the constraints of this question are:
We can only pick one
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40 Combination Sum II
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Intuition & AlgorithmI think it’s better to compare this question with last question 39 Combination Sum. Their difference is:
One number can appe
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39 Combination Sum
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Intuition && AlgorithmIt’s dfs+dynamic programming problem. To get all the possible combination adding up to the target, we need to solve seve
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47 Permutations II
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Intuition & AlgorithmRecall how we get permutations for numbers without duplication: for each permutation in last solution set, we insert the new
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46 Permutations
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Intuition & AlgorithmIt’s a dynamic programming question. Suppose we have get the permutations of i number, the i+1th number will be added to the
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49 Group Anagrams
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Intuition & AlgorithmThe primitive problem of this question is how to define anagrams. The definition from wikipedia is:
An anagram is a word or
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148 Sort List
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Intuition & AlgorithmThe diagram and illustration in the question have given us a clear description of insertion sort algorithm.
Separate the lis
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