Common techniques

1. Sorting and applying some greey idea

2. Multiset/priority queue - insert/delete based on some property

3. Reversal of approach/thinking backward

4. Splitting dimension - for example, converting a 2 D problem into couple 1D's and arguing for one dimension.

5. Classical ideas - range based etc. (finish first/last etc.)

6. classical problems - machine job allocation
   Variants - starting time, length, ending time - Earliest ending time yields the best solution

7. Multiset can be used when priority queues are used. Consider multiset as superset of PQs.

8. Knapsack - Dynamic Programming
   Fractional knapsack - Greedy
   whereas
   Activity Selection - Greedy
   Weighted Activity Selection - Dynamic Programming