Fix ambiguity errors in a_star and steiner_tree
#114
| Job | Run time |
|---|---|
| 2m 32s | |
| 2m 29s | |
| 2m 35s | |
| 2m 27s | |
| 2m 23s | |
| 4m 42s | |
| 2m 38s | |
| 2m 36s | |
| 4m 47s | |
| 3m 5s | |
| 3m 23s | |
| 5m 34s | |
| 3m 55s | |
| 3m 53s | |
| 6m 26s | |
| 7m 46s | |
| 6m 16s | |
| 7m 16s | |
| 5m 0s | |
| 5m 33s | |
| 7m 40s | |
| 1h 32m 56s |