In this post, we are going to solve the 475. Heaters problem of Leetcode. This problem 475. Heaters is a Leetcode medium level problem. Let’s see the code, 475. Heaters – Leetcode Solution.

Problem

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

Every house can be warmed, as long as the house is within the heater’s warm radius range.

Given the positions of houses and heaters on a horizontal line, return the minimum radius standard of heaters so that those heaters could cover all houses.

Notice that all the heaters follow your radius standard, and the warm radius will the same.

Example 1 :

Input: houses = [1,2,3], heaters = [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: houses = [1,2,3,4], heaters = [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.

Example 3 :

Input: houses = [1,5], heaters = [2]
Output: 3

Constraints

• 1 <= houses.length, heaters.length <= 3 * 104
• 1 <= houses[i], heaters[i] <= 109

Now, let’s see the code of 475. Heaters – Leetcode Solution.

Heaters – Leetcode Solution

475. Heaters – Solution in Java

class Solution {
    
    public boolean searchSpace(int rad,int[] house,int[] heaters){
        Arrays.sort(house);
        Arrays.sort(heaters);
        int i=0;
        for(int heater : heaters){
            int l = heater-rad, r = heater+rad;
            for(;i<house.length;i++){
                if(house[i]<l || house[i]>r)break;
            }
        }
        return i==house.length;
    }
    public int findRadius(int[] houses, int[] heaters) {
        
        
        int s = 0;
        int e = Integer.MAX_VALUE;
        int ans=0;
        while(s<=e){
            int rad = s-(s-e)/2;
            if(searchSpace(rad,houses,heaters)==true){
                ans = rad;
                e=rad-1;
            }
            else if(searchSpace(rad,houses,heaters)==false){
                s = rad+1;
            }
           
        }
        return ans;
    }
}

475. Heaters – Solution in C++

class Solution {
public:
    int findRadius(vector<int>& houses, vector<int>& heaters) {
        if (heaters.size() == 0) {
            return 0;
        }
        sort(houses.begin(), houses.end());
        sort(heaters.begin(), heaters.end());
        int radius = 0;
        int index = 0;
        for (int i = 0; i < houses.size(); i++) {
            while (index + 1 < heaters.size() && (abs(heaters[index+1] - houses[i]) <= abs(heaters[index] - houses[i]))) {
                index++;
            }
            radius = max(radius, abs(heaters[index] - houses[i]));
        }
        return radius;
    }
};

475. Heaters – Solution in Python

def findRadius(self, houses, heaters):
    heaters = sorted(heaters) + [float('inf')]
    i = r = 0
    for x in sorted(houses):
        while x >= sum(heaters[i:i+2]) / 2.:
            i += 1
        r = max(r, abs(heaters[i] - x))
    return r

Note: This problem 475. Heaters is generated by Leetcode but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.