most_stones_removed_with_same_row_or_column.go

package main

func removeStones(stones [][]int) int {
	n := len(stones)
	parent := make([]int, n)
	for i := 0; i < n; i++ {
		parent[i] = i
	}

	for i := 0; i < n; i++ {
		for j := i + 1; j < n; j++ {
			s1, s2 := stones[i], stones[j]
			if s1[0] == s2[0] || s1[1] == s2[1] {
				pi, pj := find(parent, i), find(parent, j)
				parent[pj] = pi
			}
		}
	}

	res := 0
	for i := 0; i < n; i++ {
		if parent[i] == i {
			res++
		}
	}

	return n - res
}

func find(parent []int, idx int) int {
	i := idx
	for parent[i] != i {
		i = parent[i]
	}
	parent[idx] = i
	return i
}