Create 2183-count-array-pairs-divisible-by-k.js

Author: everthis

2183-count-array-pairs-divisible-by-k.js

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+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+const coutPairs = function(nums, k) {
+  let res = 0;
+  let cnt = Array(1e5 + 1).fill(0);
+  const n = nums.length
+  for (let i = 0; i < n; ++i) {
+    if (nums[i] % k == 0) {
+      res += i;
+      ++cnt[0];
+    }
+    else {
+      let div = gcd(k, nums[i]);
+      for (let d = 0; d <= div; ++d) res += cnt[k / div * d];
+      ++cnt[div];
+    }   
+  }
+  return res;
+};
+
+function gcd(a, b) {
+  if(b === 0) return a
+  return gcd(b, a % b)
+}