Recursion problems

148 Recursion problems on CampusCode, in order. Open any for its full statement, examples and constraints.

• 687. Print 1 to N Using Recursion Easy
• 688. Print N to 1 Using Recursion Easy
• 689. Factorial of a Number Easy
• 690. Nth Fibonacci Number Easy
• 691. Sum of First N Natural Numbers Easy
• 692. Product of First N Natural Numbers Easy
• 693. Power of a Number (x^n) Easy
• 694. Sum of Digits of a Number Easy
• 695. Reverse a String Using Recursion Easy
• 696. Check Palindrome Using Recursion Easy
• 697. Count Zeros in a Number Easy
• 698. GCD of Two Numbers (Euclidean Algorithm) Easy
• 699. LCM of Two Numbers Using Recursion Easy
• 700. Find Maximum Element in Array Recursively Easy
• 701. Find Minimum Element in Array Recursively Easy
• 702. Binary Search Using Recursion Easy
• 703. Linear Search Using Recursion Easy
• 704. Count Occurrences of Element in Array Easy
• 705. Reverse an Array Using Recursion Easy
• 706. Check if Array is Sorted (Recursive) Easy
• 707. Sum of Array Elements Using Recursion Easy
• 708. Print All Elements of Array Recursively Easy
• 709. Find Index of an Element Recursively Easy
• 710. Count Digits in a Number Easy
• 711. Multiply Two Numbers Without * Operator Easy
• 712. Print Multiplication Table Using Recursion Easy
• 713. Tower of Hanoi — Minimum Moves (Modulo 10^9+7) Easy
• 714. Print All Even Numbers up to N Easy
• 715. Print All Odd Numbers up to N Easy
• 716. Sum of Even Numbers up to N Easy
• 717. Recursive Bubble Sort Easy
• 718. Recursive Insertion Sort Easy
• 719. Print Fibonacci Series up to N Terms Easy
• 720. Check if a Number is a Power of 2 Easy
• 721. Check if a Number is a Power of 3 Easy
• 722. Flatten a Nested Array Recursively Easy
• 723. Recursive String Length Easy
• 724. Count Vowels in a String Recursively Easy
• 725. Remove All Occurrences of a Character Recursively Easy
• 726. Replace Spaces with Underscores (Recursive) Easy
• 727. Concatenate N Copies of a String Easy
• 728. Is Uppercase String (Recursive Check) Easy
• 729. Convert Number to Binary Using Recursion Easy
• 730. Convert Binary to Decimal Using Recursion Easy
• 731. Nth Row of Pascal's Triangle (Modulo 10^9+7) Easy
• 732. Recursive Exponentiation (Fast Power, Modulo 10^9+7) Easy
• 733. First Occurrence of Element in Array Easy
• 734. Last Occurrence of Element in Array Easy
• 735. Move All Zeros to End (Recursive) Easy
• 736. Single Entry of Pascal's Triangle — C(n, k) (Modulo 10^9+7) Easy
• 737. Recursive Floor Division Easy
• 738. Jump Search Using Recursion Easy
• 739. Print Pattern — Right Angle Triangle (Recursive) Easy
• 740. Print Pattern — Inverted Triangle (Recursive) Easy
• 741. Check Armstrong Number Recursively Easy
• 742. Sum of Squares of First N Numbers Easy
• 743. Recursive Palindrome Number Check Easy
• 744. Compute Binomial Coefficient C(n, r) (Modulo 10^9+7) Easy
• 745. Return All Indices of Target in Array Easy
• 746. Find the Sorted Position of Element (Recursive) Easy
• 747. Tribonacci Number Easy
• 748. Digital Root (Recursive Digit Sum) Easy
• 749. Generate All Subsets (Power Set) Medium
• 750. Generate All Unique Permutations of a String Medium
• 751. Generate All Unique Permutations of an Array Medium
• 752. Letter Combinations of a Phone Number Medium
• 753. Combination Sum I (Unlimited Use) Medium
• 754. Combination Sum II (Each Element Used Once) Medium
• 755. Combination Sum III (Exactly K Numbers) Medium
• 756. Subsets II (With Duplicates) Medium
• 757. Permutations II (With Duplicates) Medium
• 758. Palindrome Partitioning Medium
• 759. Word Search in 2D Grid Medium
• 760. N-Queens with Fixed First-Queen Column (Count Solutions) Medium
• 761. Rat in a Maze — Path Exists Medium
• 762. Sudoku Solver — Solvable? Medium
• 763. Count Balanced Parentheses (Catalan, Modulo 10^9+7) Medium
• 764. Decode Ways (Recursive + Memoization, Modulo 10^9+7) Medium
• 765. Word Break (Recursive + Memoization) Medium
• 766. Flood Fill Algorithm Medium
• 767. Merge Sort Medium
• 768. Quick Sort Medium
• 769. Climb Stairs with K Steps (Modulo 10^9+7) Medium
• 770. House Robber (Recursive + Memoization) Medium
• 771. Coin Change — Minimum Coins (Recursive) Medium
• 772. Coin Change II — Count Ways (Modulo 10^9+7) Medium
• 773. Unique Paths in Grid (Recursive, Modulo 10^9+7) Medium
• 774. Count Paths from Top-Left to Bottom-Right (Modulo 10^9+7) Medium
• 775. Knapsack 0/1 (Recursive + Memoization) Medium
• 776. Longest Common Subsequence (Recursive + Memoization) Medium
• 777. Longest Increasing Subsequence (Recursive + Memoization) Medium
• 778. Edit Distance (Recursive + Memoization) Medium
• 779. Count All Paths in Directed Graph (0 to N-1) Medium
• 780. Count Binary Strings Without Consecutive 1s (Modulo 10^9+7) Medium
• 781. Tower of Hanoi — General N Disks (Modulo 10^9+7) Medium
• 782. Count Distinct Subsequences of a String (Modulo 10^9+7) Medium
• 783. Count All Subsequences with Given Sum (Modulo 10^9+7) Medium
• 784. Check if Any Subsequence Equals Target Sum Medium
• 785. Kth Symbol in Grammar Medium
• 786. Gray Code — i-th Element Using Recursion Medium
• 787. Predict the Winner (Game Theory Recursion) Medium
• 788. Beautiful Arrangement — Count with First Value Fixed Medium
• 789. Wildcard Pattern Matching (? and *) Medium
• 790. Restore IP Addresses — Count Valid Decompositions Medium
• 791. Partition Equal Subset Sum (Recursive + Memo) Medium
• 792. Target Sum — Assign +/- to Each Number (Modulo 10^9+7) Medium
• 793. Count All Paths with Obstacles in Grid (Modulo 10^9+7) Medium
• 794. Count Islands Using DFS Recursion Medium
• 795. All Possible Full Binary Trees — Count Medium
• 796. Expression Add Operators — Count Expressions Reaching Target Medium
• 797. Minimum Path Sum in Grid (Recursive + Memoization) Medium
• 798. Josephus Problem Medium
• 799. N-Queens II — Count All Solutions (Optimized) Hard
• 800. Sudoku Solver (Optimized Backtracking) Hard
• 801. Regular Expression Matching (Recursive) Hard
• 802. Wildcard Matching (Recursive + Memo) Hard
• 803. Word Break II — Count All Sentences (Modulo 10^9+7) Hard
• 804. Remove Invalid Parentheses — Count Minimum-Removal Solutions Hard
• 805. K-th Permutation Sequence Hard
• 806. Burst Balloons (Interval DP via Recursion) Hard
• 807. Count All Valid Pickup/Delivery Options (Modulo 10^9+7) Hard
• 808. Knight Dialer — Count Distinct Sequences (Modulo 10^9+7) Hard
• 809. Stickers to Spell Word (Recursive + Memo) Hard
• 810. Reconstruct Itinerary — Euler Path Exists from JFK Hard
• 811. Shortest Path Visiting All Nodes (Recursion + Bitmask) Hard
• 812. 24 Game (All Expressions with 4 Numbers) Hard
• 813. Count Arrangements of N Bishops on M×M Board Hard
• 814. Beautiful Arrangement II — Constructible? Hard
• 815. Minimum Cost to Fill Given Weight in Bag Hard
• 816. Partition to K Equal Sum Subsets Hard
• 817. Matchsticks to Square (Backtracking) Hard
• 818. Number of Squareful Arrays Hard
• 819. Tiling Problem — Count Ways to Tile 2×N Floor (Modulo 10^9+7) Hard
• 820. Egg Drop Problem (Recursive + Memo) Hard
• 821. Optimal Strategy for a Game (Coin Row) Hard
• 822. Super Egg Drop (Binary Search + Recursion) Hard
• 823. Maximum Sum Increasing Subsequence (Recursive) Hard
• 824. Count Strings Without 3 Consecutive Same Characters (Modulo 10^9+7) Hard
• 825. Find All Paths in DAG (Count, u to v) Hard
• 826. Minimum XOR Sum of Two Arrays (Bitmask Recursion) Hard
• 827. Allocate Mailboxes — DP on Sorted Array Hard
• 828. All Paths for a Sum in Binary Tree Hard
• 829. Minimum Moves to Spread Stones Over 3×3 Grid Hard
• 830. Count Special Subsequences (Mod 10^9+7) Hard
• 831. Print All K-Partitions of a String — Count (Mod 10^9+7) Hard
• 832. Zuma Game (Recursive DP) Hard
• 833. Strange Printer (Recursive Interval DP) Hard
• 834. Maximum Product of Splitted Binary Tree (Mod 10^9+7) Hard