Small fixes

algorithms/graph/bellman_ford.cpp

algorithms/graph/bipartite_match.cpp

algorithms/graph/centroid_decomposition.cpp

algorithms/graph/dijkstra.cpp

algorithms/graph/dinic.cpp

algorithms/graph/edmonds_karp.cpp

algorithms/graph/ford_fulkerson.cpp

algorithms/graph/hld.cpp

algorithms/graph/hopcroft_karp.cpp

algorithms/graph/kosaraju.cpp

algorithms/graph/lca.cpp

algorithms/graph/min_cost_max_flow.cpp

algorithms/graph/prim.cpp

algorithms/graph/tarjan.cpp

algorithms/graph/topological_sort.cpp

algorithms/graph/travelling_salesman.cpp

algorithms/math/binary_exponentiation.cpp

algorithms/math/euler_totient.cpp

algorithms/structure/segment_tree.cpp

algorithms/structure/segment_tree_2d.cpp