Easy Level

1. Heap Sort
2. Stack Data Structure (Introduction and Program)
3. Dynamic Programming | Set 10 ( 0-1 Knapsack Problem)
4. Find subarray with given sum | Set 1 (Nonnegative Numbers)
5. Given only a pointer/reference to a node to be deleted in a singly lin
6. Search in a row wise and column wise sorted matrix

Medium Level

1. Find the number of islands | Set 1 (Using DFS)
2. Find the point where maximum intervals overlap
3. Flattening a Linked List
4. Largest Sum Contiguous Subarray

Hard Level

1. Backtracking | Set 3 (N Queen Problem)