Hands of Straights

Slug: hands-of-straights

Difficulty: Medium

Id: 712344

Topic Tags: Arrays, Hash, Greedy, Sorting, Data Structures, Algorithms

Company Tags: None

Summary

The "Hands of Straights" problem involves creating a function that takes an array of integers and returns the number of ways to create hands with straights from the given numbers. A hand is considered straight if all the cards have consecutive values. The input array represents the cards in a deck, where each card has a unique value from 1 to 13 (representing Ace to King).

Detailed Explanation

To solve this problem, we can use a greedy approach. First, we sort the input array in ascending order. Then, we initialize a variable straights to keep track of the number of straights found.

Here's the step-by-step breakdown:

1. Sort the input array in ascending order.
2. Initialize a variable straights to 0.
3. Iterate through the sorted array. For each element:
   • If the current card value is consecutive to the previous card value, increment straights. This means we're finding a straight.
   • Otherwise, reset the count and start a new straight.
4. Return the total number of straights found (straights).

Here's an ASCII art diagram illustrating the process:

  [1, 2, 3, 5, 6]  // initial array
  [1, 2, 3, 5, 6]  // sorted array
  straights = 0      // initialize count

  iterate through:
    card1 = 1        // start with first card
    card2 = 2        // consecutive cards found
    straights += 1   // increment count

    card3 = 3        // consecutive cards found
    straights += 1   // increment count

    card4 = 5        // reset count, new straight started
    straights = 0     // initialize count for new straight

    card5 = 6        // consecutive cards found
    straights += 1   // increment count

  return straights = 2  // total number of straights found

The time complexity for this solution is O(n log n) due to the sorting step, where n is the length of the input array. The space complexity is O(1), as we only use a few variables to keep track of our progress.

Optimized Solutions

Java