Create 2514-count-anagrams.js

Author: everthis

2514-count-anagrams.js

@@ -0,0 +1,60 @@
+const mod = 1e9 + 7
+const fact = Array(1e5 + 2)
+getfact()
+// console.log(fact)
+/**
+ * @param {string} s
+ * @return {number}
+ */
+const countAnagrams = function (s) {
+  let ans = 1
+  const arr = s.trim().split(' ')
+  for (const word of arr) {
+    ans = modmul(ans, ways(word))
+  }
+
+  return ans
+}
+
+function modmul(a, b) {
+  const big = BigInt
+  return Number(((big(a) % big(mod)) * (big(b) % big(mod))) % big(mod))
+}
+
+function binExpo(a, b) {
+  if (b === 0) return 1
+  let res = binExpo(a, Math.floor(b / 2))
+  if (b & 1) {
+    return modmul(a, modmul(res, res))
+  } else {
+    return modmul(res, res)
+  }
+}
+
+function modmulinv(a) {
+  return binExpo(a, mod - 2)
+}
+
+function getfact() {
+  fact[0] = 1
+  for (let i = 1; i <= 100001; i++) {
+    fact[i] = modmul(fact[i - 1], i)
+  }
+}
+
+function ways(str) {
+  const freq = Array(26).fill(0)
+  const a = 'a'.charCodeAt(0)
+  for (let i = 0; i < str.length; i++) {
+    freq[str.charCodeAt(i) - a]++
+  }
+
+  let totalWays = fact[str.length]
+
+  let factR = 1
+  for (let i = 0; i < 26; i++) {
+    factR = modmul(factR, fact[freq[i]])
+  }
+  // console.log(freq, totalWays, factR)
+  return modmul(totalWays, modmulinv(factR))
+}