990. Satisfiability of Equality Equations

class Solution {
    private static class UnionFind {
        private final int[] parent;

        public UnionFind(int count) {
            this.parent = new int[count];
            for (int i = 0; i < count; i++) {
                this.parent[i] = i;
            }
        }

        public void union(int x, int y) {
            int xRoot = getRoot(x);
            int yRoot = getRoot(y);
            if (xRoot == yRoot) {
                return;
            }

            parent[xRoot] = yRoot;
        }

        public int getRoot(int x) {
            while (x != parent[x]) {
                parent[x] = parent[parent[x]]; // path compression
                x = parent[x];
            }

            return x;
        }

        public boolean isConnected(int x, int y) {
            return getRoot(x) == getRoot(y);
        }
    }

    public boolean equationsPossible(String[] equations) {
        UnionFind unionFind = new UnionFind(26);

        for (String equation : equations) {
            if (equation.charAt(1) == '=') {
                int x = equation.charAt(0) - 'a';
                int y = equation.charAt(3) - 'a';
                unionFind.union(x, y);
            }
        }

        for (String equation : equations) {
            if (equation.charAt(1) == '!') {
                int x = equation.charAt(0) - 'a';
                int y = equation.charAt(3) - 'a';
                if (unionFind.isConnected(x, y)) {
                    return false;
                }
            }
        }

        return true;
    }
}

Reference

990. Satisfiability of Equality Equations
使用并查集处理不相交集合问题（Java、Python）