add 1685

fishercoder1534 · fishercoder1534 · commit dd9ed8a171cb · 2020-12-12T10:31:58.000-08:00
diff --git a/README.md b/README.md
@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ &#9733;
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1685|[Sum of Absolute Differences in a Sorted Array](https://leetcode.com/problems/sum-of-absolute-differences-in-a-sorted-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1685.java) ||Medium|Math, Greedy|
 |1684|[Count the Number of Consistent Strings](https://leetcode.com/problems/count-the-number-of-consistent-strings/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1684.java) ||Easy|String|
 |1679|[Max Number of K-Sum Pairs](https://leetcode.com/problems/max-number-of-k-sum-pairs/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1679.java) ||Medium|HashTable|
 |1678|[Goal Parser Interpretation](https://leetcode.com/problems/goal-parser-interpretation/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1678.java) ||Easy|String|
diff --git a/src/main/java/com/fishercoder/solutions/_1685.java b/src/main/java/com/fishercoder/solutions/_1685.java
@@ -0,0 +1,22 @@
+package com.fishercoder.solutions;
+
+public class _1685 {
+    public static class Solution1 {
+        public int[] getSumAbsoluteDifferences(int[] nums) {
+            int len = nums.length;
+            int[] preSums = new int[len];
+            for (int i = 1; i < len; i++) {
+                preSums[i] = preSums[i - 1] + nums[i - 1];
+            }
+            int[] postSums = new int[len];
+            for (int i = len - 2; i >= 0; i--) {
+                postSums[i] = postSums[i + 1] + nums[i + 1];
+            }
+            int[] result = new int[len];
+            for (int i = 0; i < len; i++) {
+                result[i] = nums[i] * i - preSums[i] + postSums[i] - nums[i] * (len - i - 1);
+            }
+            return result;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1685Test.java b/src/test/java/com/fishercoder/_1685Test.java
@@ -0,0 +1,24 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1685;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertArrayEquals;
+
+public class _1685Test {
+    private static _1685.Solution1 solution1;
+    private static int[] nums;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1685.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        nums = new int[]{2, 3, 5};
+        assertArrayEquals(new int[]{4, 3, 5}, solution1.getSumAbsoluteDifferences(nums));
+    }
+
+}
