p475

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LeetCode p475 Heaters 题解

1.题目：

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

题意：

输入两个数组，第一个数组为房屋的坐标，第二个数组为火炉的坐标。
假设房屋和火炉都在同一条直线上
求可以温暖所有房屋时，火炉的最小影响范围半径。

2.解题思路:

见代码
先排序

3.代码

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public class Solution {
    public int findRadius(int[] houses, int[] heaters) {
        int ans = 0;
		int j = 0;
		int flag = 0;

		Arrays.sort(houses);
		Arrays.sort(heaters);
		// System.out.println(Arrays.toString(houses));
		// System.out.println(Arrays.toString(heaters));
		for (int i = 0; i < houses.length; i++) {

			int a = houses[i];
			if (a >= heaters[j]) {
				for (; j < heaters.length - 1; j++)

				{
					if (a >= heaters[j] && a <= heaters[j + 1]) {
						flag = 1;
						break;
					}
				}

				if (flag == 1) {
					ans = Math.max(ans,
							Math.min(a - heaters[j], heaters[j + 1] - a));
					flag = 0;

				} else {
					// j = j + 1;
					ans = Math.max(ans, a - heaters[j]);
				}
				continue;
			} else {
				ans = Math.max(ans, heaters[j] - a);
			}

		}
		return ans;
    }
}

4.一些总结：