leetcode 475 Heaters
z
 2019-04-25 00:11:21  

Winter is coming! Your first job during the contest is to design a standard heater with fixed warm radius to warm all the houses.

Now, you are given positions of houses and heaters on a horizontal line, find out minimum radius of heaters so that all houses could be covered by those heaters.

So, your input will be the positions of houses and heaters seperately, and your expected output will be the minimum radius standard of heaters.

Note:

  1. Numbers of houses and heaters you are given are non-negative and will not exceed 25000.
  2. Positions of houses and heaters you are given are non-negative and will not exceed 10^9.
  3. As long as a house is in the heaters’ warm radius range, it can be warmed.
  4. All the heaters follow your radius standard and the warm radius will the same.

Example 1:

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Input: [1,2,3],[2]
Output: 1
Explanation: The only heater was placed in the position 2, and if we use the radius 1 standard, then all the houses can be warmed.

Example 2:

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Input: [1,2,3,4],[1,4]
Output: 1
Explanation: The two heater was placed in the position 1 and 4. We need to use radius 1 standard, then all the houses can be warmed.
  • 需要找到每一个房间和它最近的火炉的距离的最小值得最大值。
  • 直观的方法是双重遍历。
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class Solution {
    public int findRadius(int[] houses, int[] heaters) {
        int longest = 0;
        for (int house: houses) {
            int temp = Integer.MAX_VALUE;
            for (int heater: heaters) {
                int distance = Math.abs(house-heater);
                temp = Math.min(temp, distance);
            }
            longest = Math.max(longest, temp);
        }
        return longest;
    }
}

但是这样的话，时间复杂度很高。

  • 如果我们对houses和heaters进行排序的话，假设我们顺序