Phase 2 / prefix-sum, simulation
Phase 2 / dp, range-query
Phase 5 / 0-1-bfs, graph
Phase 2 / monotonic-stack, subarray
Phase 3 / circular, parity, modular-groups
Phase 3 / permutation, cycles, greedy
Phase 2 / segment-tree, modular-arithmetic
Phase 2 / sliding-window, inclusion-exclusion
Phase 2 / dp, coloring, grid
Phase 3 / tree, lca, frequency
Phase 2 / greedy, strings
Phase 2 / bitwise, segment-tree