交换字符使得字符串相同

/*
 * Problem: We have two strings s1 and s2 of the same length, containing only the characters 'x' and 'y'. We want to make them identical by swapping characters between the two strings. The goal is to find the minimum number of swaps needed, or return -1 if it is not possible.
 *
 * Approach using Java Streams:
 * 1. Use IntStream to iterate over the strings and count the number of 'xy' and 'yx' mismatches.
 * 2. Apply the same logic as the regular Java approach to determine the number of swaps.
 */

import java.util.stream.IntStream;

public int minimumSwapStream(String s1, String s2) {
    long xy_count = IntStream.range(0, s1.length())
                            .filter(i -> s1.charAt(i) == 'x' && s2.charAt(i) == 'y')
                            .count();
    long yx_count = IntStream.range(0, s1.length())
                            .filter(i -> s1.charAt(i) == 'y' && s2.charAt(i) == 'x')
                            .count();

    if ((xy_count + yx_count) % 2 != 0) {
        return -1;
    }

    return (int)(xy_count / 2 + yx_count / 2 + (xy_count % 2) * 2);
}