839. Similar String Groups

Poison
2023-06-13
UnionFind
class Solution {
    private static class UnionFind {

        private final int[] parent;
        private int count;

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

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

            parent[rootX] = rootY;
            count--;
        }

        private int getRoot(int x) {
            while (parent[x] != 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 int getCount() {
            return count;
        }
    }

    public int numSimilarGroups(String[] strs) {
        UnionFind unionFind = new UnionFind(strs.length);
        for (int i = 0; i < strs.length; i++) {
            for (int j = i + 1; j < strs.length; j++) {
                if (!unionFind.isConnected(i, j) && isSimilar(strs, i, j)) {
                    unionFind.union(i, j);
                }
            }
        }

        return unionFind.getCount();
    }

    private boolean isSimilar(String[] strs, int i, int j) {
        String strA = strs[i], strB = strs[j];
        int diff = 0;
        for (int k = 0; k < strA.length(); k++) {
            if (strA.charAt(k) != strB.charAt(k)) {
                diff++;
            }
        }

        return diff <= 2;
    }
}
References
