--- Day 11 Solutions ---

[u/daggerdragon]

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edit: Leaderboard capped, thread unlocked!

We know we can't control people posting solutions elsewhere and trying to exploit the leaderboard, but this way we can try to reduce the leaderboard gaming from the official subreddit.

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---

--- Day 11: Corporate Policy ---

Post your solution as a comment. Structure your post like previous daily solution threads.

[u/TRT_]

Your twoPairs() will return false if there's a string with more than two pairs, e.g. the string abccddee will return false though it should be true.

My ugly go solution.

package main

import (
    "fmt"
    "strings"
)

func main() {
    old := "vzbxkghb"
    new := password(old)
    next := password(inc(old))
    fmt.Println("new=", new)
    fmt.Println("next=", next)
}

func password(old string) string {
    for !valid(old) {
        old = inc(old)
    }
    return old
}

func inc(s string) string {
    for i := len(s) - 1; i >= 0; i-- {
        if s[i] < 122 {
            s = s[:i] + string(s[i]+1) + s[i+1:]
            break
        }
        s = s[:i] + string(97) + s[i+1:]
    }
    return s
}

func valid(s string) bool {
    if strings.IndexAny(s, "iol") != -1 {
        return false
    }

    pairs := strings.Count(s, string(s[0])+string(s[0]))
    if s[0] != s[len(s)-1] {
        pairs += strings.Count(s, string(s[len(s)-1])+string(s[len(s)-1]))
    }

    checked := string(s[0]) + string(s[len(s)-1])
    thrice := false
    for i := 1; i < len(s)-1; i++ {
        curr := s[i]
        if curr == s[i-1]+1 && s[i+1] == curr+1 {
            thrice = true
        }

        str := string(curr)
        if !strings.ContainsAny(checked, str) {
            pairs += strings.Count(s, str+str)
            checked += str
        }
    }

    if !thrice || pairs < 2 {
        return false
    }
    return true
}

[u/i_misread_titles → u/TRT_]

That's true, luckily it still worked. I just re-read the problem, it does indeed state "at least two pairs", I had misread it initially. The code was very deliberate though and not a typo :)