Just programming

  Below is the important Graph Algorithms for problem solving Algorithms Cycle Detection Algorithm  For Directed graph Cycle can be detected using : 1) DFS-Based Cycle Detection using  color marking (visited array)     void dfs(node):       mark visited       for neighbor:          if not visited:              dfs(neighbor)        stack.push(node) 2) Kahn’s Algorithm : Build the Graph → Create an adjacency list from the prerequisites array. Compute In-Degree → Count the number of prerequisites (incoming edges) for each course. Start BFS with Zero In-Degree Nodes → Add all courses with zero prerequisites to a queue. Process Courses in BFS Order → Remove edges and reduce in-degrees. Check if All Courses Were Taken → If all courses were processed, return true ; otherwise, there’s a cycle.     // Simple idea of Kahn's: while (queue is n...

                                    Meeting Room 1 and Meeting Room 2 of Leetcode 252. Meeting Rooms Given an array of meeting time  intervals  where  intervals[i] = [start i , end i ] , determine if a person could attend all meetings. Example 1: Input: intervals = [[0,30],[5,10],[15,20]] Output: false Example 2: Input: intervals = [[7,10],[2,4]] Output: true Solution: Sort according to Ending time. public boolean canAttendMeetings ( int [][] intervals ) { Arrays . sort (intervals, ( int [] a, int [] b) -> { return a[ 1 ] - b[ 1 ]; }); int n = intervals . length ; for ( int i = 1 ;i<n;i++){ int st = intervals[i][ 0 ]; int en = intervals[i][ 1 ]; if (st < intervals[i- 1 ][ 1 ]){ return false ; } } return true ; }