Add solution #3463

Author: JoshCrozier

README.md

@@ -844,6 +844,7 @@
 3452|[Sum of Good Numbers](./3452-sum-of-good-numbers.js)|Easy|
 3461|[Check If Digits Are Equal in String After Operations I](./3461-check-if-digits-are-equal-in-string-after-operations-i.js)|Easy|
 3462|[Maximum Sum With at Most K Elements](./3462-maximum-sum-with-at-most-k-elements.js)|Medium|
+3463|[Check If Digits Are Equal in String After Operations II](./3463-check-if-digits-are-equal-in-string-after-operations-ii.js)|Hard|
 
 ## License
 

solutions/3463-check-if-digits-are-equal-in-string-after-operations-ii.js

@@ -0,0 +1,63 @@
+/**
+ * 3463. Check If Digits Are Equal in String After Operations II
+ * https://leetcode.com/problems/check-if-digits-are-equal-in-string-after-operations-ii/
+ * Difficulty: Hard
+ *
+ * You are given a string s consisting of digits. Perform the following operation repeatedly until
+ * the string has exactly two digits:
+ * - For each pair of consecutive digits in s, starting from the first digit, calculate a new digit
+ *   as the sum of the two digits modulo 10.
+ * - Replace s with the sequence of newly calculated digits, maintaining the order in which they
+ *   are computed.
+ *
+ * Return true if the final two digits in s are the same; otherwise, return false.
+ */
+
+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+var hasSameDigits = function(s) {
+  const n = s.length;
+  const binomialMod2 = (k, n) => (k & n) === k ? 1 : 0;
+  const binomialMod5 = (k, n) => {
+    if (k > n) return 0;
+    let result = 1;
+    const pascalMod5 = [
+      [1, 0, 0, 0, 0],
+      [1, 1, 0, 0, 0],
+      [1, 2, 1, 0, 0],
+      [1, 3, 3, 1, 0],
+      [1, 4, 1, 4, 1]
+    ];
+
+    while (k > 0 || n > 0) {
+      const ki = k % 5;
+      const ni = n % 5;
+      if (ki > ni) return 0;
+      result = (result * pascalMod5[ni][ki]) % 5;
+      k = Math.floor(k / 5);
+      n = Math.floor(n / 5);
+    }
+    return result;
+  };
+
+  const binomialMod10 = (k, n) => {
+    const mod2 = binomialMod2(k, n);
+    const mod5 = binomialMod5(k, n);
+    for (let i = 0; i < 10; i++) {
+      if (i % 2 === mod2 && i % 5 === mod5) return i;
+    }
+    return 0;
+  };
+
+  let sum1 = 0;
+  let sum2 = 0;
+  for (let i = 0; i <= n - 2; i++) {
+    const coeff = binomialMod10(i, n - 2);
+    sum1 = (sum1 + coeff * +s[i]) % 10;
+    sum2 = (sum2 + coeff * +s[i + 1]) % 10;
+  }
+
+  return sum1 === sum2;
+};