589. N-ary Tree Preorder Traversal
Given the root of an n-ary tree, return the preorder traversal of its nodes’ values.
Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)
Given an integer n, return an array ans of length n + 1 such that for each i (0 <= i <= n), ans[i] is the number of 1’s in the binary representation of i.
The next greater element of some element x in an array is the first greater element that is to the right of x in the same array.
You are given two distinct 0-indexed integer arrays nums1 and nums2, where nums1 is a subset of nums2.
For each 0 <= i < nums1.length, find the index j such that nums1[i] == nums2[j] and determine the next greater element of nums2[j] in nums2. If there is no next greater element, then the answer for this query is -1.
Return an array ans of length nums1.length such that ans[i] is the next greater element as described above.
You are given a list of equivalent string pairs synonyms where synonyms[i] = [si, ti] indicates that si and ti are equivalent strings. You are also given a sentence text.
Return all possible synonymous sentences sorted lexicographically.
1061. Lexicographically Smallest Equivalent String
You are given two strings of the same length s1 and s2 and a string baseStr.
We say s1[i] and s2[i] are equivalent characters.
- For example, if s1 = “abc” and s2 = “cde”, then we have ‘a’ == ‘c’, ‘b’ == ‘d’, and ‘c’ == ‘e’.
Equivalent characters follow the usual rules of any equivalence relation:
- Reflexivity: ‘a’ == ‘a’.
- Symmetry: ‘a’ == ‘b’ implies ‘b’ == ‘a’.
- Transitivity: ‘a’ == ‘b’ and ‘b’ == ‘c’ implies ‘a’ == ‘c’.
For example, given the equivalency information from s1 = “abc” and s2 = “cde”, “acd” and “aab” are equivalent strings of baseStr = “eed”, and “aab” is the lexicographically smallest equivalent string of baseStr.
Return the lexicographically smallest equivalent string of baseStr by using the equivalency information from s1 and s2.
1639. Number of Ways to Form a Target String Given a Dictionary
You are given a list of strings of the same length words and a string target.
Your task is to form target using the given words under the following rules:
- target should be formed from left to right.
- To form the ith character (0-indexed) of target, you can choose the kth character of the jth string in words if target[i] = words[j][k].
- Once you use the kth character of the jth string of words, you can no longer use the xth character of any string in words where x <= k. In other words, all characters to the left of or at index k become unusuable for every string.
- Repeat the process until you form the string target.
Notice that you can use multiple characters from the same string in words provided the conditions above are met.
Return the number of ways to form target from words. Since the answer may be too large, return it modulo 109 + 7.