We want to split a group of n people (labeled from 1 to n) into two groups of any size. Each person may dislike some other people, and they should not go into the same group.
Given the integer n and the array dislikes where dislikes[i] = [ai, bi] indicates that the person labeled ai does not like the person labeled bi, return true if it is possible to split everyone into two groups in this way.
1349. Maximum Students Taking Exam
Given a m * n matrix seats that represent seats distributions in a classroom. If a seat is broken, it is denoted by ‘#’ character otherwise it is denoted by a ‘.’ character.
Students can see the answers of those sitting next to the left, right, upper left and upper right, but he cannot see the answers of the student sitting directly in front or behind him. Return the maximum number of students that can take the exam together without any cheating being possible..
Students must be placed in seats in good condition.
1655. Distribute Repeating Integers
You are given an array of n integers, nums, where there are at most 50 unique values in the array. You are also given an array of m customer order quantities, quantity, where quantity[i] is the amount of integers the ith customer ordered. Determine if it is possible to distribute nums such that:
- The ith customer gets exactly quantity[i] integers,
- The integers the ith customer gets are all equal, and
- Every customer is satisfied.
Return true if it is possible to distribute nums according to the above conditions.
You are given the root of a binary tree. We install cameras on the tree nodes where each camera at a node can monitor its parent, itself, and its immediate children.
Return the minimum number of cameras needed to monitor all nodes of the tree.
Every valid email consists of a local name and a domain name, separated by the ‘@’ sign. Besides lowercase letters, the email may contain one or more ‘.’ or ‘+’.
- For example, in “alice@leetcode.com”, “alice” is the local name, and “leetcode.com” is the domain name.
If you add periods ‘.’ between some characters in the local name part of an email address, mail sent there will be forwarded to the same address without dots in the local name. Note that this rule does not apply to domain names.
- For example, “alice.z@leetcode.com” and “alicez@leetcode.com” forward to the same email address.
If you add a plus ‘+’ in the local name, everything after the first plus sign will be ignored. This allows certain emails to be filtered. Note that this rule does not apply to domain names.
- For example, “m.y+name@email.com” will be forwarded to “my@email.com”.
It is possible to use both of these rules at the same time.
Given an array of strings emails where we send one email to each emails[i], return the number of different addresses that actually receive mails.
1489. Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree
Given a weighted undirected connected graph with n vertices numbered from 0 to n - 1, and an array edges where edges[i] = [ai, bi, weighti] represents a bidirectional and weighted edge between nodes ai and bi. A minimum spanning tree (MST) is a subset of the graph’s edges that connects all vertices without cycles and with the minimum possible total edge weight.
Find all the critical and pseudo-critical edges in the given graph’s minimum spanning tree (MST). An MST edge whose deletion from the graph would cause the MST weight to increase is called a critical edge. On the other hand, a pseudo-critical edge is that which can appear in some MSTs but not all.
Note that you can return the indices of the edges in any order.
You are given an n x n integer matrix grid where each value grid[i][j] represents the elevation at that point (i, j).
The rain starts to fall. At time t, the depth of the water everywhere is t. You can swim from a square to another 4-directionally adjacent square if and only if the elevation of both squares individually are at most t. You can swim infinite distances in zero time. Of course, you must stay within the boundaries of the grid during your swim.
Return the least time until you can reach the bottom right square (n - 1, n - 1) if you start at the top left square (0, 0).
We are given n different types of stickers. Each sticker has a lowercase English word on it.
You would like to spell out the given string target by cutting individual letters from your collection of stickers and rearranging them. You can use each sticker more than once if you want, and you have infinite quantities of each sticker.
Return the minimum number of stickers that you need to spell out target. If the task is impossible, return -1.
Note: In all test cases, all words were chosen randomly from the 1000 most common US English words, and target was chosen as a concatenation of two random words.
1125. Smallest Sufficient Team
In a project, you have a list of required skills req_skills, and a list of people. The ith person people[i] contains a list of skills that the person has.
Consider a sufficient team: a set of people such that for every required skill in req_skills, there is at least one person in the team who has that skill. We can represent these teams by the index of each person.
- For example, team = [0, 1, 3] represents the people with skills people[0], people[1], and people[3].
Return any sufficient team of the smallest possible size, represented by the index of each person. You may return the answer in any order.
It is guaranteed an answer exists.
1325. Delete Leaves With a Given Value
Given a binary tree root and an integer target, delete all the leaf nodes with value target.
Note that once you delete a leaf node with value target, if its parent node becomes a leaf node and has the value target, it should also be deleted (you need to continue doing that until you cannot).