1 public class Solution {
 2     public int findRadius(int[] houses, int[] heaters) {
 3         Arrays.sort(houses);
 4         Arrays.sort(heaters);
 5         int index = 0;
 6         int radis = 0;
 7         if (houses[0] < heaters[0]) radis = heaters[0] - houses[0];
 8         for (int i = 0; i < heaters.length; ) {
 9             // all unvisited houses left to heater[i] should be less than current radis
10             // some unvisited houses right to heater[i] may also less than current radis
11             // break when 1. invalid index, 2. houses right to heater[i] larger than current radis
12             while (index < houses.length && (houses[index] <= heaters[i] || houses[index] - heaters[i] <= radis)) index++;
13             if (index == houses.length) break;
14             // have unvisited heaters
15             // here we meet first house out of range on the right
16             if (i < heaters.length - 1) {
17                 // house is right to next heater, we could update radis when processing next heater
18                 // because this house will still break in while loop
19                 if (heaters[i + 1] <= houses[index]) {
20                     i++;
21                 } else {
22                     // next heater is right to current house, the house has to be in the range of current heater,
23                     // need to update radis
24                     // do not update heater index, we may meet more houses have to be covered by this heater
25                     if (heaters[i + 1] - houses[index] > houses[index] - heaters[i]) {
26                         radis = Math.max(houses[index] - heaters[i], radis);
27                     } else {
28                         // next heater will cover current house
29                         radis = Math.max(heaters[i + 1] - houses[index], radis);
30                         i++;
31                     }
32                     // radis determined by current house is done
33                     index++;
34                 }
35             } else {
36                 // no unvisited heaters, this last house out of range of current radis, update radis
37                 radis = houses[houses.length - 1] - heaters[i];
38                 break;
39             }
40         }
41         return radis;
42     }
43 }

 1 public int findRadius(int[] houses, int[] heaters) {
 2     Arrays.sort(heaters);
 3     int result = 0;
 4
 5     for (int house : houses) {
 6         int index = Arrays.binarySearch(heaters, house);
 7         if (index < 0) {
 8             index = ~index;
 9             int dist1 = index - 1 >= 0 ? house - heaters[index - 1] : Integer.MAX_VALUE;
10             int dist2 = index < heaters.length ? heaters[index] - house : Integer.MAX_VALUE;
11
12             result = Math.max(result, Math.min(dist1, dist2));
13         }
14     }
15
16     return result;
17 }

 1 public class Solution {
 2     public int findRadius(int[] houses, int[] heaters) {
 3         Arrays.sort(houses);
 4         Arrays.sort(heaters);
 5
 6         int i = 0, res = 0;
 7         for (int house : houses) {
 8             while (i < heaters.length - 1 && heaters[i] + heaters[i + 1] <= house * 2) {
 9                 i++;
10             }
11             res = Math.max(res, Math.abs(heaters[i] - house));
12         }
13
14         return res;
15     }
16 }