Function advent_solutions::advent2017::day01::part2 [−] [src]

pub fn part2(input: &str) -> u32

You notice a progress bar that jumps to 50% completion. Apparently, the door isn't yet satisfied, but it did emit a star as encouragement. The instructions change:

Now, instead of considering the next digit, it wants you to consider the digit halfway around the circular list. That is, if your list contains 10 items, only include a digit in your sum if the digit 10/2 = 5 steps forward matches it. Fortunately, your list has an even number of elements.

For example:

1212 produces 6: the list contains 4 items, and all four digits match the digit 2 items ahead.
```
assert_eq!(part2("1212"), 6);
```
1221 produces 0, because every comparison is between a 1 and a 2.
```
assert_eq!(part2("1221"), 0);
```
123425 produces 4, because both 2s match each other, but no other digit has a match.
```
assert_eq!(part2("123425"), 4);
```
123123 produces 12.
```
assert_eq!(part2("123123"), 12);
```
12131415 produces 4.
```
assert_eq!(part2("12131415"), 4);
```

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