Code Added

Author: anjha1

1721.swapping-nodes-in-a-linked-list/README.md

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+# [1721. Swapping Nodes in a Linked List](https://leetcode.com/problems/swapping-nodes-in-a-linked-list/)
+

1721.swapping-nodes-in-a-linked-list/SwappingNodesInALinkedList.java

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+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class SwappingNodesInALinkedList {
+    public ListNode swapNodes(ListNode head, int k) {
+        ListNode curr = head, first = head, last = head;
+        int count = 1;
+        while (curr.next != null) {
+            if (count < k) {
+                first = first.next;
+            } else {
+                last = last.next;
+            }
+            count++;
+            curr = curr.next;
+        }
+        int temp = first.val;
+        first.val = last.val;
+        last.val = temp;
+        return head;
+    }
+}

1768.merge-strings-alternately/MergeStringsAlternately.java

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+class MergeStringsAlternately {
+    public String mergeAlternately(String word1, String word2) {
+        int n = word1.length(), m = word2.length();
+        int i = 0, j = 0;
+        StringBuilder res = new StringBuilder();
+        while (i < n || j < m) {
+            if (i < n) {
+                res.append(word1.charAt(i++));
+            }
+            if (j < m) {
+                res.append(word2.charAt(j++));
+            }
+        }
+
+        return res.toString();
+    }
+}

1768.merge-strings-alternately/README.md

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+# [1768. Merge Strings Alternately](https://leetcode.com/problems/merge-strings-alternately/)
+
+
+Complexity Analysis:
+
+- Time Complexity: $O(n+m)$. $n$ is the length of `word1` and $m$ is the length of `word2`.
+- Space Complexity: $O(1)$.

1770.maximum-score-from-performing-multiplication-operations/MaximumScoreFromPerformingMultiplicationOperations.java

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+import java.util.Arrays;
+
+class MaximumScoreFromPerformingMultiplicationOperations {
+    public int maximumScore(int[] nums, int[] multipliers) {
+        int n = nums.length;
+        int m = multipliers.length;
+        int[][] dp = new int[m+1][m+1];
+
+        for (int op = m - 1; op >= 0; op--) {
+            for (int left = op; left >= 0; left--) {
+                dp[op][left] = Math.max(multipliers[op] * nums[left] + dp[op + 1][left + 1], multipliers[op] * nums[n - 1 - (op - left)] + dp[op + 1][left]);
+            }
+        }
+
+        return dp[0][0];
+    }
+}

1770.maximum-score-from-performing-multiplication-operations/README.md

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+# [1770. Maximum Score from Performing Multiplication Operations](https://leetcode.com/problems/maximum-score-from-performing-multiplication-operations/)
+