🎨 reverse bits, product of array except self Solution

product-of-array-except-self/dalpang81.java

@@ -0,0 +1,23 @@
+/*
+* 시간복잡도: O(n)
+* 공간복잡도: O(1)
+* */
+class Solution {
+    public int[] productExceptSelf(int[] nums) {
+        int n = nums.length;
+        int[] answer = new int[n];
+
+        answer[0] = 1;
+        for (int i = 1; i < n; i++) {
+            answer[i] = answer[i - 1] * nums[i - 1];
+        }
+
+        int suffixProduct = 1;
+        for (int i = n - 1; i >= 0; i--) {
+            answer[i] *= suffixProduct;
+            suffixProduct *= nums[i];
+        }
+
+        return answer;
+    }
+}

reverse-bits/dalpang81.java

@@ -0,0 +1,16 @@
+/*
+* 시간복잡도: O(1)
+* 공간복잡도: O(1)
+* */
+public class Solution {
+    // you need treat n as an unsigned value
+    public int reverseBits(int n) {
+        int result = 0;
+        for (int i = 0; i < 32; i++) {
+            result <<= 1;
+            result |= (n & 1);
+            n >>= 1;
+        }
+        return result;
+    }
+}