Study of Euler circuits

Euler loop problems:

Is it possible to go from one point to the next, and each side just goes back to the starting point?

The Euler circuit of the non-direction graph:

If each vertex in the graph has an even number of degrees, you can draw a line from the starting point to the terminating point, which is the Euler loop of the graph without direction;

The Euler circuit of the graph:

If the degree of each vertex of the graph is equal to the degree of entry, then a line can be drawn from the starting point to the terminating point, which is the Euler loop of the direction graph;

The ring algorithm of Euler loop:

1. Determine if there is a euro-pull circuit;

2. Look for the ring p1-p2-p3 from I-... px; (p1=px, i.e. the starting and ending points are the same)

3. Mark the P1 to PX for the status to be looked up;

4. Take the 2nd step for each point you want to find, i.e. recursively find the ring, and insert the newly found ring into the ring of the previous layer to get P1-P2-.. PJ-1-Q1-Q2-... qy-pj+1-pj+2...-px (Q1 the same as the original PJ);

Study of Euler circuits