풀이1. Product of Array Except Self #239

Author: seungseung88

product-of-array-except-self/seungseung88.js

@@ -0,0 +1,42 @@
+/**
+ * 시간복잡도: O(n)
+ *  - 첫번째 for문 O(n)
+ *  - 두번째 for문 O(n)
+ *
+ * 공간 복잡도: O(1)
+ *  - 추가 배열 생성 X
+ */
+const productExceptSelf = (nums) => {
+  let multiplyResult = 1;
+  let countZero = 0;
+
+  for (let i = 0; i < nums.length; i += 1) {
+    if (nums[i] === 0) {
+      countZero += 1;
+
+      if (countZero >= 2) {
+        multiplyResult = 0;
+        break;
+      }
+
+      continue;
+    }
+    multiplyResult *= nums[i];
+  }
+
+  for (let i = 0; i < nums.length; i += 1) {
+    if (countZero === 1) {
+      if (nums[i] === 0) {
+        nums[i] = multiplyResult;
+      } else {
+        nums[i] = 0;
+      }
+    } else if (countZero >= 2) {
+      nums[i] = 0;
+    } else {
+      nums[i] = multiplyResult / nums[i];
+    }
+  }
+
+  return nums;
+};