For 1149D - Abandoning Roads I implemented this code using a priority queue. This is tutorials logic. And took 639ms.

But when I implemented same logic using a single normal queue it took 280ms. ( My code ).

Can any one tell me why without priority queue Dijkstra working much faster. Please help me to understand the complexity for 2nd code ( without priority queue ) . I understood the complexity of the 1st code ( with priority queue ).