add 2869

Author: fishercoder1534

Diff for: paginated_contents/algorithms/3rd_thousand/README.md

@@ -7,6 +7,7 @@
 | 2942 | [Find Words Containing Character](https://leetcode.com/problems/find-words-containing-character/)                                                                                                             | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2942.java)                                       |                                      | Easy                                     |
 | 2937 | [Make Three Strings Equal](https://leetcode.com/problems/make-three-strings-equal/)                                                                                                             | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2937.java)                                       |                                      | Easy                                     |
 | 2873 | [Maximum Value of an Ordered Triplet I](https://leetcode.com/problems/maximum-value-of-an-ordered-triplet-i/)                                                                                                             | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2873.java)                                       |                                      | Easy                                     |
+| 2869 | [Minimum Operations to Collect Elements](https://leetcode.com/problems/minimum-operations-to-collect-elements/)                                                                                                             | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2869.java)                                       |                                      | Easy                                     |
 | 2864 | [Maximum Odd Binary Number](https://leetcode.com/problems/maximum-odd-binary-number/)                                                                                                             | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2864.java)                                       |                                      | Easy                                     |Greedy
 | 2839 | [Check if Strings Can be Made Equal With Operations I](https://leetcode.com/problems/check-if-strings-can-be-made-equal-with-operations-i/)                                                                                                          | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2839.java)                                       |                                      | Easy                                     |
 | 2833 | [Furthest Point From Origin](https://leetcode.com/problems/furthest-point-from-origin/)                                                                                                          | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2833.java)                                       |                                      | Easy                                     |

Diff for: src/main/java/com/fishercoder/solutions/thirdthousand/_2869.java

@@ -0,0 +1,23 @@
+package com.fishercoder.solutions.thirdthousand;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public class _2869 {
+    public static class Solution1 {
+        public int minOperations(List<Integer> nums, int k) {
+            Set<Integer> set = new HashSet<>();
+            for (int i = 1; i <= k; i++) {
+                set.add(i);
+            }
+            for (int i = nums.size() - 1; i >= 0; i--) {
+                set.remove(nums.get(i));
+                if (set.size() == 0) {
+                    return nums.size() - i;
+                }
+            }
+            return -1;
+        }
+    }
+}