Which nodes are the source and sink in the example flow network?

Conditions

• Refers to the specific hand-drawn example network shown in the video.
• The network is arranged roughly from left to right.

Reasoning, step by step

1. Observe the example flow network diagram.
2. Identify the node on the far left as the starting point of the flow.
3. Identify the node on the far right as the ending point of the flow.
4. Note the labels $S$ (Source) and $T$ or $E$ (Sink) assigned to these nodes.

Example

The presenter draws a six-node network and states, 'we give this to be the source and this is the sink T,' labeling the leftmost node S and the rightmost node T. Later, in the annotated version, the rightmost node is labeled E and identified as the sink.

Common misconceptions

• Assuming any node can be the source or sink without specific designation.
• Confusing intermediate nodes (like a, b, c, d) with the source or sink.
• Believing the source must always be at the top or the sink at the bottom, rather than following the left-to-right flow direction shown.

Watch the explanation

Explore next

• What is a flow network in graph terms?
• How do you read the numbers on the edges of a flow network diagram?
• What is the difference between flow and capacity in a network?