Create 996-number-of-squareful-arrays.js

Author: everthis

996-number-of-squareful-arrays.js

@@ -0,0 +1,45 @@
+/**
+ * @param {number[]} A
+ * @return {number}
+ */
+
+const numSquarefulPerms = function(A) {
+  const cntMap = {};
+  const squareMap = {};
+  let cnt = 0;
+  for (let num of A) {
+    if (!cntMap.hasOwnProperty(num)) {
+      cntMap[num] = 1;
+      squareMap[num] = new Set();
+    } else {
+      cntMap[num] = cntMap[num] + 1;
+    }
+  }
+
+  for (let num1 of Object.keys(cntMap)) {
+    for (let num2 of Object.keys(cntMap)) {
+      let c = Math.sqrt(+num1 + +num2);
+      if (c === Math.floor(c)) {
+        squareMap[num1].add(+num2);
+        squareMap[num2].add(+num1);
+      }
+    }
+  }
+  for (let num of Object.keys(cntMap)) {
+    countPerm(num, A.length - 1);
+  }
+  return cnt;
+  function countPerm(num, left) {
+    cntMap[num] = cntMap[num] - 1;
+    if (left === 0) {
+      cnt++;
+    } else {
+      for (let next of squareMap[num]) {
+        if (cntMap[next] !== 0) {
+          countPerm(next, left - 1);
+        }
+      }
+    }
+    cntMap[num] = cntMap[num] + 1;
+  }
+};