LeetCode 2938: Separate Black and White Balls Solution

Master LeetCode problem 2938 (Separate Black and White Balls), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

2938. Separate Black and White Balls

Medium

Two Pointers String Greedy

Problem Explanation

Explanation:

To solve this problem, we can iterate through the string and count the number of black balls that are to the left of their correct positions. The minimum number of steps required will be equal to this count, as each swap operation can move one black ball to the right. We can calculate this count by iterating through the string from left to right and keeping track of the number of black balls encountered. Solution:

Solution Code

public int minSwaps(String s) {
    int blackCount = 0;
    int misplacedBlacks = 0;
    
    for (char c : s.toCharArray()) {
        if (c == '1') {
            blackCount++;
        } else {
            misplacedBlacks += blackCount;
        }
    }
    
    return misplacedBlacks;
}

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Frequently Asked Questions

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