Detonate the Maximum Bombs - Graph & BFS/DFS [JS]

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Description 

Solution 1: Graph & DFS

  1. Build a directed graph for all the bombs,
    bombs[i] is connected to bombs[j] if the distance between the two points are smaller than or equal to the radius of bombs[i].
  2. Recursively DFS from each bomb and record the maximum number of points reached from each bomb.

Time Complexity: O(n^2) 370ms
Space Complexity: O(n^2) 50.7MB

var maximumDetonation = function(bombs) {
  let n = bombs.length, graph = Array(n).fill(0).map(() => []);
  for (let i = 0; i < n; i++) {
    for (let j = 0; j < n; j++) {
      if (i === j) continue;
      let [x1, y1, radius] = bombs[i], [x2, y2] = bombs[j];
      if (getDist([x1, y1], [x2, y2]) <= radius) {
        graph[i].push(j);
      }
    }
  }
  let ans = 0;
  for (let i = 0; i < n; i++) {
    ans = Math.max(ans, dfs(i, Array(n).fill(0)));
  }
  return ans;
  
  function dfs(node, seen) {
    if (seen[node]) return 0;
    seen[node] = 1;
    if (graph[node].length === 0) return 1;
    let ans = 0;
    for (let nei of graph[node]) {
      ans += dfs(nei, seen);
    }
    return ans + 1;
  }
  
  function getDist(p1, p2) {
    let [x1, y1] = p1, [x2, y2] = p2;
    let calc1 = (x2 - x1) * (x2 - x1), calc2 = (y2 - y1) * (y2 - y1);
    return Math.sqrt(calc1 + calc2);
  }
};

Solution 2: Graph & BFS

The same as solution 1, except using BFS instead of DFS.

Time Complexity: O(n^2) 385ms
Space Complexity: O(n^2) 51.9MB

var maximumDetonation = function(bombs) {
  let n = bombs.length, graph = Array(n).fill(0).map(() => []);
  for (let i = 0; i < n; i++) {
    for (let j = 0; j < n; j++) {
      if (i === j) continue;
      let [x1, y1, radius] = bombs[i], [x2, y2] = bombs[j];
      if (getDist([x1, y1], [x2, y2]) <= radius) {
        graph[i].push(j);
      }
    }
  }
  let ans = 0;
  for (let i = 0; i < n; i++) {
    ans = Math.max(ans, bfs(i));
  }
  return ans;
  
  function bfs(node) {
    let seen = Array(n).fill(0), queue = [node], count = 0;
    seen[node] = 1;
    while (queue.length) {
      let node = queue.shift();
      count++;
      for (let nei of graph[node]) {
        if (seen[nei]) continue;
        queue.push(nei);
        seen[nei] = 1;
      }
    }
    return count;
  }
  
  function getDist(p1, p2) {
    let [x1, y1] = p1, [x2, y2] = p2;
    let calc1 = (x2 - x1) * (x2 - x1), calc2 = (y2 - y1) * (y2 - y1);
    return Math.sqrt(calc1 + calc2);
  }
};

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Location: Auckland, New Zealand

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