#include "leetcode.h" class Solution { public: int longestPath(vector &parent, string s) { int n = parent.size(), ans = 1; queue q; vector cnt(n), top1(n, 1), top2(n, 1); for (int i = 1; i < n; ++i) ++cnt[parent[i]]; for (int i = 1; i < n; ++i) if (cnt[i] == 0) q.push(i); while (!q.empty() && q.front() != 0) { int i = q.front(), p = parent[i]; q.pop(); if (int len = 1 + (s[i] != s[p] ? top1[i] : 0); top1[p] <= len) { top2[p] = top1[p]; top1[p] = len; } else top2[p] = max(top2[p], len); if (--cnt[p] == 0) { q.push(p); ans = max(ans, top1[p] + top2[p] - 1); } } return ans; } }; int main() { Solution obj; vector parent1 = {-1, 0, 0, 1, 1, 2}, parent2 = {-1, 0, 0, 0}; cout << obj.longestPath(parent1, "abacbe") << endl; // expect: 3 cout << obj.longestPath(parent2, "aabc") << endl; // expect: 3 }