LESSON 319 OF 348 · DYNAMIC PROGRAMMING

Binary Strings With K Ones in Scala

Practice O(n * k)

Given two non-negative integers N and K, return the number of binary strings of length N with exactly K ones

Example:

Input: N = 4, K = 2
Output: 6
Explanation: [
    "1100",
    "1010",
    "1001",
    "0110",
    "0101",
    "0011"
]

Notes: K <= N <= 30

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