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Author: 10coder

FindAllDuplicates.java

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+import java.util.ArrayList;
+import java.util.List;
+
+//https://leetcode.com/problems/find-all-duplicates-in-an-array/
+public class FindAllDuplicates {
+
+    //Approach:
+    // As given that numbers in array are postive and in the range of array.length
+    //while iterating make the value at index as negative before making it negative check if it is already negative means
+    // it is already visited hence the index would be duplicate value as it is already visited
+
+
+
+    public List<Integer> findDuplicates(int[] nums) {
+        List<Integer> res = new ArrayList<>();
+        for(int i=0;i<nums.length;i++) {
+            if(nums[Math.abs(nums[i])-1]<0) {
+                res.add(Math.abs(nums[i]));
+            } else {
+                nums[Math.abs(nums[i])-1]*=-1;
+            }
+        }
+        return res;
+    }
+}
+
+
+//Similar would be the approach for finding all disappeared numbers in the array, while iterating make all values at the
+// index as negatives and iterate through the array again to find all postive values and add the indexes into the result