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Description

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.

Solutions

Python3

class Solution:
    def minCostConnectPoints(self, points: List[List[int]]) -> int:
        INF = 0x3F3F3F3F
        n = len(points)
        g = [[0] * n for _ in range(n)]
        for i in range(n):
            for j in range(n):
                if i != j:
                    x1, y1 = points[i]
                    x2, y2 = points[j]
                    g[i][j] = abs(x1 - x2) + abs(y1 - y2)
        dist = [INF] * n
        vis = [False] * n
        ans = 0
        for i in range(n):
            t = -1
            for j in range(n):
                if not vis[j] and (t == -1 or dist[t] > dist[j]):
                    t = j
            if i:
                ans += dist[t]
            for j in range(n):
                dist[j] = min(dist[j], g[t][j])
            vis[t] = True
        return ans
class Solution:
    def minCostConnectPoints(self, points: List[List[int]]) -> int:
        def find(x):
            if p[x] != x:
                p[x] = find(p[x])
            return p[x]

        g = []
        n = len(points)
        for i, (x1, y1) in enumerate(points):
            for j in range(i + 1, n):
                x2, y2 = points[j]
                g.append((abs(x1 - x2) + abs(y1 - y2), i, j))
        g.sort()
        p = list(range(n))
        ans = 0
        for cost, i, j in g:
            if find(i) == find(j):
                continue
            p[find(i)] = find(j)
            n -= 1
            ans += cost
            if n == 1:
                return ans
        return 0

Java

class Solution {
    private static final int INF = 0x3f3f3f3f;

    public int minCostConnectPoints(int[][] points) {
        int n = points.length;
        int[][] g = new int[n][n];
        int[] dist = new int[n];
        boolean[] vis = new boolean[n];
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n; ++j) {
                if (i != j) {
                    int x1 = points[i][0], y1 = points[i][1];
                    int x2 = points[j][0], y2 = points[j][1];
                    g[i][j] = Math.abs(x1 - x2) + Math.abs(y1 - y2);
                }
            }
        }
        Arrays.fill(dist, INF);
        int ans = 0;
        for (int i = 0; i < n; ++i) {
            int t = -1;
            for (int j = 0; j < n; ++j) {
                if (!vis[j] && (t == -1 || dist[t] > dist[j])) {
                    t = j;
                }
            }
            if (i > 0) {
                ans += dist[t];
            }
            for (int j = 0; j < n; ++j) {
                dist[j] = Math.min(dist[j], g[t][j]);
            }
            vis[t] = true;
        }
        return ans;
    }
}
class Solution {
    private int[] p;

    public int minCostConnectPoints(int[][] points) {
        int n = points.length;
        List<int[]> g = new ArrayList<>();
        for (int i = 0; i < n; ++i) {
            int x1 = points[i][0], y1 = points[i][1];
            for (int j = i + 1; j < n; ++j) {
                int x2 = points[j][0], y2 = points[j][1];
                g.add(new int[] {Math.abs(x1 - x2) + Math.abs(y1 - y2), i, j});
            }
        }
        g.sort(Comparator.comparingInt(a -> a[0]));
        p = new int[n];
        for (int i = 0; i < n; ++i) {
            p[i] = i;
        }
        int ans = 0;
        for (int[] e : g) {
            int cost = e[0], i = e[1], j = e[2];
            if (find(i) == find(j)) {
                continue;
            }
            p[find(i)] = find(j);
            ans += cost;
            if (--n == 1) {
                return ans;
            }
        }
        return 0;
    }

    private int find(int x) {
        if (p[x] != x) {
            p[x] = find(p[x]);
        }
        return p[x];
    }
}

C++

class Solution {
public:
    const int inf = 0x3f3f3f3f;

    int minCostConnectPoints(vector<vector<int>>& points) {
        int n = points.size();
        vector<vector<int>> g(n, vector<int>(n));
        vector<int> dist(n, inf);
        vector<bool> vis(n);
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n; ++j) {
                if (i != j) {
                    int x1 = points[i][0], y1 = points[i][1];
                    int x2 = points[j][0], y2 = points[j][1];
                    g[i][j] = abs(x1 - x2) + abs(y1 - y2);
                }
            }
        }
        int ans = 0;
        for (int i = 0; i < n; ++i) {
            int t = -1;
            for (int j = 0; j < n; ++j) {
                if (!vis[j] && (t == -1 || dist[t] > dist[j])) {
                    t = j;
                }
            }
            if (i) ans += dist[t];
            for (int j = 0; j < n; ++j) dist[j] = min(dist[j], g[t][j]);
            vis[t] = true;
        }
        return ans;
    }
};
class Solution {
public:
    vector<int> p;

    int minCostConnectPoints(vector<vector<int>>& points) {
        int n = points.size();
        vector<vector<int>> g;
        for (int i = 0; i < n; ++i)
        {
            int x1 = points[i][0], y1 = points[i][1];
            for (int j = i + 1; j < n; ++j)
            {
                int x2 = points[j][0], y2 = points[j][1];
                g.push_back({abs(x1 - x2) + abs(y1 - y2), i, j});
            }
        }
        sort(g.begin(), g.end());
        p.resize(n);
        for (int i = 0; i < n; ++i) p[i] = i;
        int ans = 0;
        for (auto& e : g)
        {
            int cost = e[0], i = e[1], j = e[2];
            if (find(i) == find(j)) continue;
            p[find(i)] = find(j);
            ans += cost;
            if (--n == 1) return ans;
        }
        return 0;
    }

    int find(int x) {
        if (p[x] != x) p[x] = find(p[x]);
        return p[x];
    }
};

Go

func minCostConnectPoints(points [][]int) int {
	n := len(points)
	inf := 0x3f3f3f3f
	g := make([][]int, n)
	dist := make([]int, n)
	vis := make([]bool, n)
	for i, p1 := range points {
		dist[i] = inf
		g[i] = make([]int, n)
		for j, p2 := range points {
			if i != j {
				x1, y1 := p1[0], p1[1]
				x2, y2 := p2[0], p2[1]
				g[i][j] = abs(x1-x2) + abs(y1-y2)
			}
		}
	}
	ans := 0
	for i := 0; i < n; i++ {
		t := -1
		for j := 0; j < n; j++ {
			if !vis[j] && (t == -1 || dist[t] > dist[j]) {
				t = j
			}
		}
		if i > 0 {
			ans += dist[t]
		}
		for j := 0; j < n; j++ {
			dist[j] = min(dist[j], g[t][j])
		}
		vis[t] = true
	}
	return ans
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}
func minCostConnectPoints(points [][]int) int {
	n := len(points)
	var g [][]int
	for i, p := range points {
		x1, y1 := p[0], p[1]
		for j := i + 1; j < n; j++ {
			x2, y2 := points[j][0], points[j][1]
			g = append(g, []int{abs(x1-x2) + abs(y1-y2), i, j})
		}
	}
	sort.Slice(g, func(i, j int) bool {
		return g[i][0] < g[j][0]
	})
	ans := 0
	p := make([]int, n)
	for i := range p {
		p[i] = i
	}
	var find func(x int) int
	find = func(x int) int {
		if p[x] != x {
			p[x] = find(p[x])
		}
		return p[x]
	}
	for _, e := range g {
		cost, i, j := e[0], e[1], e[2]
		if find(i) == find(j) {
			continue
		}
		p[find(i)] = find(j)
		ans += cost
		n--
		if n == 1 {
			return ans
		}
	}
	return 0
}

func abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}

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