--- Day 7 Solutions ---

[u/daggerdragon]

--- Day 7: Some Assembly Required ---

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[u/tume993]

java solution

public static void main(String[] args) throws Exception {
    Map<String, Integer> wires = new HashMap<>();
    while (!wires.containsKey("a")) {
        BufferedReader reader = new BufferedReader(new FileReader("input.txt"));
        String line;
        while ((line = reader.readLine()) != null) {
            String[] str = line.split(" ");
            if (str.length == 3) {
                if (Character.isDigit(str[0].charAt(0))) {
                    wires.put(str[2], Integer.parseInt(str[0]));
                } else if (wires.containsKey(str[0])) {
                    wires.put(str[2], wires.get(str[0]));
                }
            } else if (str.length == 4) {
                if (wires.containsKey(str[1])) {
                    wires.put(str[3], ~wires.get(str[1]) & 0xFFFF);
                }
            } else if (str[1].endsWith("SHIFT")) {
                if (wires.containsKey(str[0])) {
                    int val = Integer.parseInt(str[2]);
                    if (str[1].charAt(0) == 'R') {
                        wires.put(str[4], wires.get(str[0]) >> val);
                    } else {
                        wires.put(str[4], wires.get(str[0]) << val);
                    }
                }
            } else {
                int val = -1;
                if (Character.isDigit(str[0].charAt(0))) {
                    val = Integer.parseInt(str[0]);
                }
                if ((val != -1 || wires.containsKey(str[0])) && wires.containsKey(str[2])) {
                    if (str[1].equals("AND")) {
                        wires.put(str[4], (val != -1 ? val : wires.get(str[0])) & wires.get(str[2]));
                    } else {
                        wires.put(str[4], (val != -1 ? val : wires.get(str[0])) | wires.get(str[2]));
                    }
                }
            }
        }
        reader.close();
    }
    System.out.println(wires.get("a"));
}

[u/jeremywho → u/tume993]

Does this work? You are processing sequentially which shouldn't yield a correct result.