Create 2791-count-paths-that-can-form-a-palindrome-in-a-tree.js

Author: everthis

2791-count-paths-that-can-form-a-palindrome-in-a-tree.js

@@ -0,0 +1,47 @@
+/**
+ * @param {number[]} parent
+ * @param {string} s
+ * @return {number}
+ */
+const countPalindromePaths = function (parent, s) {
+  let n = parent.length
+  let dp = Array(n).fill(undefined)
+  dp[0] = 0
+
+  function getDp(x) {
+    if (dp[x] != undefined) return dp[x]
+    dp[x] = getDp(parent[x]) ^ getMask(s[x])
+    return dp[x]
+  }
+
+  for (let i = 1; i < n; i++) getDp(i)
+  dp.sort((a, b) => a - b)
+  let counter = {}
+  let res = 0
+
+  for (let i = 0; i <= n; i++) {
+    if (counter[dp[i]]) counter[dp[i]]++
+    else {
+      counter[dp[i]] = 1
+
+      if (i) {
+        let temp = dp[i - 1]
+        let cntPrev = counter[temp]
+        let c = 0
+
+        while (temp) {
+          let b = temp & -temp
+          c += counter[dp[i - 1] ^ b] ?? 0
+          temp ^= b
+        }
+
+        res += c * cntPrev + (cntPrev * (cntPrev - 1)) / 2
+      }
+    }
+  }
+
+  return res
+}
+function getMask(c) {
+  return 1 << (c.charCodeAt() - 97)
+}