Iter through each house and find the left and right heater. Choose the MAX of left, right heater distance.

```
public int findRadius(int[] houses, int[] heaters) {
if(houses == null || houses.length == 0) return 0;
Arrays.sort(houses);
Arrays.sort(heaters);
int ans = 0;
int index = 0;
for(int house: houses) {
while(index< heaters.length && house > heaters[index]) index++;
int leftDis = index-1 < 0? Integer.MAX_VALUE: house - heaters[index-1];
int rightDis = index >= heaters.length? Integer.MAX_VALUE: heaters[index] - house;
int dis = Math.min(leftDis, rightDis);
ans = Math.max(ans, dis);
}
return ans;
}
```