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Diffstat (limited to 'longest_path_diff_adjacent_char.cpp')
-rw-r--r-- | longest_path_diff_adjacent_char.cpp | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/longest_path_diff_adjacent_char.cpp b/longest_path_diff_adjacent_char.cpp new file mode 100644 index 0000000..0f60da9 --- /dev/null +++ b/longest_path_diff_adjacent_char.cpp @@ -0,0 +1,48 @@ +// 2246. Longest Path With Different Adjacent Characters +#include "leetcode.h" + +/* + * you are given a tree (ie. a connected undirected graph that has no cycles) + * rooted at node '0' consisting of 'n' nodes numbered from '0' to 'n - 1'. the + * tree is represented by a 0-indexed array 'parent' of size 'n' where + * 'parent[i]' is the parent of node 'i'. since node 0 is the root, 'parent[0] = + * -1'. you are also given a string 's' of length 'n', where 's[i]' is the + * character assigned to node 'i'. return the legnth of the longest path in the + * tree such that no pair of adjacnet nodes on the path have the same character + * assigned to them. + */ + +class Solution { +public: + int longestPath(vector<int> &parent, string s) { + int n = parent.size(), ans = 1; + queue<int> q; + vector<int> 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]) + q.push(i); + while (!q.empty() && q.front()) { + 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<int> p1 = {-1, 0, 0, 1, 1, 2}, p2 = {-1, 0, 0, 0}; + printf("%d\n", obj.longestPath(p1, "abacbe")); // expect: 3 + printf("%d\n", obj.longestPath(p2, "aabc")); // expect: 3 +} |