1var longestPath = function(parent, s) {
2    const n = parent.length;
3    const children = Array.from({ length: n }, () => []);
4    for (let i = 1; i < n; i++) {
5        children[parent[i]].push(i);
6    }
7
8    let maxLength = 0;
9
10    const dfs = (node) => {
11        let firstLongest = 0, secondLongest = 0;
12        for (const child of children[node]) {
13            const childLength = dfs(child);
14            if (s[node] !== s[child]) {
15                if (childLength > firstLongest) {
16                    secondLongest = firstLongest;
17                    firstLongest = childLength;
18                } else if (childLength > secondLongest) {
19                    secondLongest = childLength;
20                }
21            }
22        }
23        maxLength = Math.max(maxLength, firstLongest + secondLongest + 1);
24        return firstLongest + 1;
25    };
26
27    dfs(0);
28    return maxLength;
29};