LeetCode in Kotlin

1584. Min Cost to Connect All Points

Medium

You are given an array points representing integer coordinates of some points on a 2D-plane, where points[i] = [xi, yi].

The cost of connecting two points [xi, yi] and [xj, yj] is the manhattan distance between them: |xi - xj| + |yi - yj|, where |val| denotes the absolute value of val.

Return the minimum cost to make all points connected. All points are connected if there is exactly one simple path between any two points.

Example 1:

Input: points = [[0,0],[2,2],[3,10],[5,2],[7,0]]

Output: 20

Explanation:

We can connect the points as shown above to get the minimum cost of 20.

Notice that there is a unique path between every pair of points.

Example 2:

Input: points = [[3,12],[-2,5],[-4,1]]

Output: 18

Constraints:

• 1 <= points.length <= 1000
• -106 <= xi, yi <= 106
• All pairs (xi, yi) are distinct.

Solution

import java.util.PriorityQueue

class Solution {
    fun minCostConnectPoints(points: Array<IntArray>): Int {
        val v = points.size
        if (v == 2) {
            return getDistance(points[0], points[1])
        }
        val pq = PriorityQueue(v, Pair())
        val mst = BooleanArray(v)
        val dist = IntArray(v)
        val parent = IntArray(v)
        dist.fill(1000000)
        parent.fill(-1)
        dist[0] = 0
        parent[0] = 0
        for (i in 0 until v) {
            pq.add(Pair(dist[i], i))
        }
        constructMST(parent, points, mst, pq, dist)
        var cost = 0
        for (i in 1 until parent.size) {
            cost += getDistance(points[parent[i]], points[i])
        }
        return cost
    }

    private fun constructMST(
        parent: IntArray,
        points: Array<IntArray>,
        mst: BooleanArray,
        pq: PriorityQueue<Pair>,
        dist: IntArray,
    ) {
        if (!containsFalse(mst)) {
            return
        }
        val newPair = pq.poll()
        val pointIndex: Int = newPair.v
        mst[pointIndex] = true
        for (i in parent.indices) {
            val d = getDistance(points[pointIndex], points[i])
            if (!mst[i] && d < dist[i]) {
                dist[i] = d
                pq.add(Pair(dist[i], i))
                parent[i] = pointIndex
            }
        }
        constructMST(parent, points, mst, pq, dist)
    }

    private fun containsFalse(mst: BooleanArray): Boolean {
        for (b in mst) {
            if (!b) {
                return true
            }
        }
        return false
    }

    private fun getDistance(p1: IntArray, p2: IntArray): Int {
        return Math.abs(p1[0] - p2[0]) + Math.abs(p1[1] - p2[1])
    }

    class Pair : Comparator<Pair> {
        var dis = 0
        var v = 0

        constructor()
        constructor(dis: Int, v: Int) {
            this.dis = dis
            this.v = v
        }

        override fun compare(p1: Pair, p2: Pair): Int {
            return p1.dis - p2.dis
        }
    }
}

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