|
| 1 | +--- |
| 2 | +id: min-cost-to-connect-all-points |
| 3 | +title: Min Cost to Connect All Points |
| 4 | +sidebar_label: 1584 - Min Cost to Connect All Points |
| 5 | +tags: |
| 6 | +- Array |
| 7 | +- Union Find |
| 8 | +- Graph |
| 9 | +- Minimum Spanning Tree |
| 10 | +description: "This is a solution to the Min Cost to Connect All Points problem on LeetCode." |
| 11 | +--- |
| 12 | + |
| 13 | +## Problem Description |
| 14 | +You are given an array points representing integer coordinates of some points on a 2D-plane, where `points[i] = [xi, yi].` |
| 15 | + |
| 16 | +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. |
| 17 | + |
| 18 | +Return the minimum cost to make all points connected. All points are connected if there is exactly one simple path between any two points. |
| 19 | + |
| 20 | +### Examples |
| 21 | +**Example 1:** |
| 22 | + |
| 23 | +``` |
| 24 | +Input: points = [[0,0],[2,2],[3,10],[5,2],[7,0]] |
| 25 | +Output: 20 |
| 26 | +Explanation: |
| 27 | + |
| 28 | +We can connect the points as shown above to get the minimum cost of 20. |
| 29 | +Notice that there is a unique path between every pair of points. |
| 30 | +
|
| 31 | +``` |
| 32 | + |
| 33 | +### Constraints |
| 34 | +- `1 <= points.length <= 1000` |
| 35 | +- `-10^6 <= xi, yi <= 10^6` |
| 36 | +- `All pairs (xi, yi) are distinct.` |
| 37 | + |
| 38 | +## Solution for Min Cost to Connect All Points |
| 39 | +### Approach |
| 40 | +#### Prim's algorithm: |
| 41 | + |
| 42 | +- Prim's algorithm is an algorithm for solving the optimization problem of finding the minimum spanning tree in a weighted connected graph within graph theory. A minimum spanning tree is a subset of the edges of the graph that forms a tree containing all vertices while minimizing the total weight of those edges. |
| 43 | + |
| 44 | +#### Overview of the Algorithm: |
| 45 | + |
| 46 | +- Calculate the distances between each pair of points and use Prim's algorithm to form the minimum spanning tree. |
| 47 | +- Start from an initial point, mark it as visited, and select the point with the smallest distance among the unvisited points. |
| 48 | +- Calculate the distances from the selected point to the unvisited points and store them in a cache. |
| 49 | +- Add the minimum cost edge to the priority queue using the distances from the cache. |
| 50 | +- Repeat the above steps until all points are visited, and calculate the minimum cost. |
| 51 | +#### Specific Steps: |
| 52 | + |
| 53 | +#### Initial State: |
| 54 | + |
| 55 | +- n: Number of points |
| 56 | +- min_cost: Minimum cost (initially 0) and return value |
| 57 | +- visited: A list to indicate if each point is visited (initially all False) |
| 58 | +- pq: Priority queue (initially (0, 0) indicating starting from point 0 with cost 0) |
| 59 | +- cache: Dictionary for caching distances (initially empty) |
| 60 | +#### Each Step: |
| 61 | + |
| 62 | +- Pop cost and point from pq (start from the initial point). |
| 63 | +- If the point is already visited, skip this point. |
| 64 | +- Otherwise, mark this point as visited and add the current cost to the minimum cost. |
| 65 | +- Calculate distances from this point to all unvisited points and store them in the cache. Update the cache if the new distance is smaller. |
| 66 | +- Add the point with the smallest distance among the unvisited points to the priority queue using distances from the cache. |
| 67 | +- Repeat steps 3 to 5 until all points are visited. |
| 68 | +- Return the final minimum cost. |
| 69 | + |
| 70 | + |
| 71 | +<Tabs> |
| 72 | + <TabItem value="Solution" label="Solution"> |
| 73 | + |
| 74 | + #### Implementation |
| 75 | + ```jsx live |
| 76 | + function Solution(arr) { |
| 77 | + var minCostConnectPoints = function(points) { |
| 78 | + let cost = 0; |
| 79 | + const n = points.length; |
| 80 | + const dist = Array(n).fill(Infinity); |
| 81 | + dist[0] = 0; |
| 82 | + let next = 0; |
| 83 | + |
| 84 | + for (let step = 1; step < n; step++) { |
| 85 | + let min = Infinity; |
| 86 | + let point = -1; |
| 87 | + for (let i = 1; i < n; i++) { |
| 88 | + if (dist[i] > 0) { |
| 89 | + dist[i] = Math.min(dist[i], Math.abs(points[i][0] - points[next][0]) + Math.abs(points[i][1] - points[next][1])); |
| 90 | + if (dist[i] < min) { |
| 91 | + min = dist[i]; |
| 92 | + point = i; |
| 93 | + } |
| 94 | + } |
| 95 | + } |
| 96 | + cost += min; |
| 97 | + dist[point] = 0; |
| 98 | + next = point; |
| 99 | + } |
| 100 | + |
| 101 | + return cost; |
| 102 | + }; |
| 103 | + const input = [[0,0],[2,2],[3,10],[5,2],[7,0]] |
| 104 | + const output =minCostConnectPoints(input) |
| 105 | + return ( |
| 106 | + <div> |
| 107 | + <p> |
| 108 | + <b>Input: </b> |
| 109 | + {JSON.stringify(input)} |
| 110 | + </p> |
| 111 | + <p> |
| 112 | + <b>Output:</b> {output.toString()} |
| 113 | + </p> |
| 114 | + </div> |
| 115 | + ); |
| 116 | + } |
| 117 | + ``` |
| 118 | + |
| 119 | + #### Complexity Analysis |
| 120 | + |
| 121 | + - Time Complexity: $O(n^2 * log(n)) $ |
| 122 | + - Space Complexity: $ O(n)$ |
| 123 | + |
| 124 | + ## Code in Different Languages |
| 125 | + <Tabs> |
| 126 | + <TabItem value="JavaScript" label="JavaScript"> |
| 127 | + <SolutionAuthor name="@hiteshgahanolia"/> |
| 128 | + ```javascript |
| 129 | + manhattDist(v1, v2) { |
| 130 | + return Math.abs(v1[0] - v2[0]) + Math.abs(v1[1] - v2[1]); |
| 131 | + } |
| 132 | + |
| 133 | + minCostConnectPoints(points) { |
| 134 | + const n = points.length; |
| 135 | + const adj = Array.from({ length: n }, () => []); |
| 136 | + |
| 137 | + for (let i = 0; i < n; i++) { |
| 138 | + for (let j = i + 1; j < n; j++) { |
| 139 | + const dist = this.manhattDist(points[i], points[j]); |
| 140 | + adj[i].push([j, dist]); |
| 141 | + adj[j].push([i, dist]); |
| 142 | + } |
| 143 | + } |
| 144 | + |
| 145 | + const pq = new MinPriorityQueue({ priority: x => x[0] }); |
| 146 | + const vis = Array(n).fill(false); |
| 147 | + pq.enqueue([0, 0]); |
| 148 | + let cost = 0; |
| 149 | + |
| 150 | + while (!pq.isEmpty()) { |
| 151 | + const [topEdgwWt, currNode] = pq.dequeue().element; |
| 152 | + |
| 153 | + if (vis[currNode]) continue; |
| 154 | + vis[currNode] = true; |
| 155 | + cost += topEdgwWt; |
| 156 | + |
| 157 | + for (const [adjPoint, edWt] of adj[currNode]) { |
| 158 | + if (!vis[adjPoint]) { |
| 159 | + pq.enqueue([edWt, adjPoint]); |
| 160 | + } |
| 161 | + } |
| 162 | + } |
| 163 | + |
| 164 | + return cost; |
| 165 | + } |
| 166 | + ``` |
| 167 | + |
| 168 | + </TabItem> |
| 169 | + <TabItem value="TypeScript" label="TypeScript"> |
| 170 | + <SolutionAuthor name="@hiteshgahanolia"/> |
| 171 | + ```typescript |
| 172 | + class Solution { |
| 173 | + manhattDist(v1: number[], v2: number[]): number { |
| 174 | + return Math.abs(v1[0] - v2[0]) + Math.abs(v1[1] - v2[1]); |
| 175 | + } |
| 176 | +
|
| 177 | + minCostConnectPoints(points: number[][]): number { |
| 178 | + const n = points.length; |
| 179 | + const adj: [number, number][][] = Array.from({ length: n }, () => []); |
| 180 | +
|
| 181 | + for (let i = 0; i < n; i++) { |
| 182 | + for (let j = i + 1; j < n; j++) { |
| 183 | + const dist = this.manhattDist(points[i], points[j]); |
| 184 | + adj[i].push([j, dist]); |
| 185 | + adj[j].push([i, dist]); |
| 186 | + } |
| 187 | + } |
| 188 | +
|
| 189 | + const pq = new MinPriorityQueue({ priority: (x: [number, number]) => x[0] }); |
| 190 | + const vis = Array(n).fill(false); |
| 191 | + pq.enqueue([0, 0]); |
| 192 | + let cost = 0; |
| 193 | +
|
| 194 | + while (!pq.isEmpty()) { |
| 195 | + const [topEdgwWt, currNode] = pq.dequeue().element; |
| 196 | +
|
| 197 | + if (vis[currNode]) continue; |
| 198 | + vis[currNode] = true; |
| 199 | + cost += topEdgwWt; |
| 200 | +
|
| 201 | + for (const [adjPoint, edWt] of adj[currNode]) { |
| 202 | + if (!vis[adjPoint]) { |
| 203 | + pq.enqueue([edWt, adjPoint]); |
| 204 | + } |
| 205 | + } |
| 206 | + } |
| 207 | +
|
| 208 | + return cost; |
| 209 | + } |
| 210 | +} |
| 211 | +
|
| 212 | + ``` |
| 213 | + </TabItem> |
| 214 | + <TabItem value="Python" label="Python"> |
| 215 | + <SolutionAuthor name="@hiteshgahanolia"/> |
| 216 | + ```python |
| 217 | + import heapq |
| 218 | +
|
| 219 | +class Solution: |
| 220 | + def manhattDist(self, v1, v2): |
| 221 | + return abs(v1[0] - v2[0]) + abs(v1[1] - v2[1]) |
| 222 | +
|
| 223 | + def minCostConnectPoints(self, points): |
| 224 | + n = len(points) |
| 225 | + adj = [[] for _ in range(n)] |
| 226 | +
|
| 227 | + for i in range(n): |
| 228 | + for j in range(i + 1, n): |
| 229 | + dist = self.manhattDist(points[i], points[j]) |
| 230 | + adj[i].append((j, dist)) |
| 231 | + adj[j].append((i, dist)) |
| 232 | +
|
| 233 | + pq = [(0, 0)] # (distance, point) |
| 234 | + vis = [False] * n |
| 235 | + cost = 0 |
| 236 | +
|
| 237 | + while pq: |
| 238 | + topEdgwWt, currNode = heapq.heappop(pq) |
| 239 | +
|
| 240 | + if vis[currNode]: |
| 241 | + continue |
| 242 | + vis[currNode] = True |
| 243 | + cost += topEdgwWt |
| 244 | +
|
| 245 | + for adjPoint, edWt in adj[currNode]: |
| 246 | + if not vis[adjPoint]: |
| 247 | + heapq.heappush(pq, (edWt, adjPoint)) |
| 248 | +
|
| 249 | + return cost |
| 250 | +
|
| 251 | + ``` |
| 252 | + |
| 253 | + </TabItem> |
| 254 | + <TabItem value="Java" label="Java"> |
| 255 | + <SolutionAuthor name="@hiteshgahanolia"/> |
| 256 | + ```java |
| 257 | + import java.util.*; |
| 258 | +
|
| 259 | +class Solution { |
| 260 | + private int manhattDist(int[] v1, int[] v2) { |
| 261 | + return Math.abs(v1[0] - v2[0]) + Math.abs(v1[1] - v2[1]); |
| 262 | + } |
| 263 | +
|
| 264 | + public int minCostConnectPoints(int[][] points) { |
| 265 | + int n = points.length; |
| 266 | + List<List<int[]>> adj = new ArrayList<>(); |
| 267 | +
|
| 268 | + for (int i = 0; i < n; i++) { |
| 269 | + adj.add(new ArrayList<>()); |
| 270 | + } |
| 271 | +
|
| 272 | + for (int i = 0; i < n; i++) { |
| 273 | + for (int j = i + 1; j < n; j++) { |
| 274 | + int dist = manhattDist(points[i], points[j]); |
| 275 | + adj.get(i).add(new int[]{j, dist}); |
| 276 | + adj.get(j).add(new int[]{i, dist}); |
| 277 | + } |
| 278 | + } |
| 279 | +
|
| 280 | + PriorityQueue<int[]> pq = new PriorityQueue<>(Comparator.comparingInt(a -> a[0])); |
| 281 | + boolean[] vis = new boolean[n]; |
| 282 | + pq.add(new int[]{0, 0}); // {distance, point} |
| 283 | + int cost = 0; |
| 284 | +
|
| 285 | + while (!pq.isEmpty()) { |
| 286 | + int[] curr = pq.poll(); |
| 287 | + int topEdgwWt = curr[0]; |
| 288 | + int currNode = curr[1]; |
| 289 | +
|
| 290 | + if (vis[currNode]) continue; |
| 291 | + vis[currNode] = true; |
| 292 | + cost += topEdgwWt; |
| 293 | +
|
| 294 | + for (int[] neighbor : adj.get(currNode)) { |
| 295 | + int adjPoint = neighbor[0]; |
| 296 | + int edWt = neighbor[1]; |
| 297 | + if (!vis[adjPoint]) { |
| 298 | + pq.add(new int[]{edWt, adjPoint}); |
| 299 | + } |
| 300 | + } |
| 301 | + } |
| 302 | +
|
| 303 | + return cost; |
| 304 | + } |
| 305 | +} |
| 306 | +
|
| 307 | + ``` |
| 308 | + |
| 309 | + |
| 310 | + </TabItem> |
| 311 | + <TabItem value="C++" label="C++"> |
| 312 | + <SolutionAuthor name="@hiteshgahanolia"/> |
| 313 | + ```cpp |
| 314 | + class Solution { |
| 315 | +public: |
| 316 | + int manhattDist(vector<int>&v1 , vector<int>&v2) |
| 317 | + { |
| 318 | + return abs(abs(v1[0]-v2[0]) + abs(v1[1]-v2[1])); |
| 319 | + } |
| 320 | + int minCostConnectPoints(vector<vector<int>>& points) { |
| 321 | + int n = points.size(); |
| 322 | + vector<pair<int,int>> adj[n]; //{point , cost or Manhattan dist} |
| 323 | +
|
| 324 | + //we have to make a adjacency list fom every point to every other point |
| 325 | + for(int i=0; i<n ; i++) |
| 326 | + { |
| 327 | + for(int j=i+1;j<n ; j++) |
| 328 | + { |
| 329 | + adj[i].push_back({j , manhattDist(points[i] , points[j])}); |
| 330 | + adj[j].push_back({i , manhattDist(points[i] , points[j])}); |
| 331 | + } |
| 332 | + } |
| 333 | +
|
| 334 | + priority_queue<pair<int,int> , vector<pair<int,int>> , greater<pair<int,int>> > pq; |
| 335 | + // {distance , point} |
| 336 | + vector<int> vis(n,0); |
| 337 | + pq.push({0,0}); //starting from 0 as source |
| 338 | + int Cost=0; |
| 339 | + while(!pq.empty()) |
| 340 | + { |
| 341 | + auto it = pq.top(); |
| 342 | + pq.pop(); |
| 343 | + int CurrNode = it.second ; |
| 344 | + int topEdgwWt = it.first; |
| 345 | + |
| 346 | + if(vis[CurrNode]==1) continue; |
| 347 | + |
| 348 | + vis[CurrNode]=1; |
| 349 | + |
| 350 | + Cost+=topEdgwWt; |
| 351 | + for(auto it: adj[CurrNode]) |
| 352 | + { |
| 353 | + int adjPoint=it.first; |
| 354 | + int edWt=it.second; |
| 355 | + if(!vis[adjPoint]) |
| 356 | + { |
| 357 | + pq.push({edWt , adjPoint}); |
| 358 | + } |
| 359 | + } |
| 360 | + } |
| 361 | + return Cost; |
| 362 | + } |
| 363 | +}; |
| 364 | +``` |
| 365 | +</TabItem> |
| 366 | +</Tabs> |
| 367 | + |
| 368 | + </TabItem> |
| 369 | +</Tabs> |
| 370 | + |
| 371 | +## References |
| 372 | + |
| 373 | +- **LeetCode Problem**: [ Min Cost to Connect All Points](https://leetcode.com/problems/min-cost-to-connect-all-points/description/) |
| 374 | + |
| 375 | +- **Solution Link**: [LeetCode Solution](https://leetcode.com/problems/min-cost-to-connect-all-points/description/) |
| 376 | + |
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