This question can be easily solved with the help of set in O(N) time and space complexity.First add all the elements of array into set and then traverse each element of array and check whether K-ar[i] is present in set or not. Here is the code in java with O(N) complexity : boolean flag=false; HashSet<Long> … Read more
To understand this, the very first thing you need to know is that what is the difference between substring and subsequence substring is a continuous part or subpart of a string whereas subsequence is the part of a string or sequence, that might be continuous or not but the order of the elements is maintained … Read more
Consider an array: {1,2,3,4} Subarray: contiguous sequence in an array i.e. {1,2},{1,2,3} Subsequence: Need not to be contiguous, but maintains order i.e. {1,2,4} Subset: Same as subsequence except it has empty set i.e. {1,3},{} Given an array/sequence of size n, possible Subarray = n*(n+1)/2 Subseqeunce = (2^n) -1 (non-empty subsequences) Subset = 2^n