Minimum Time to Build Blocks in C++

Suppose we have a list of blocks, if we have blocks[i] = t, this means that the i-th block needs t units of time to be built. A block can only be built by exactly one worker. Single worker can either split into two workers or build a block then go home. These two decisions take some time. The time cost of spliting one worker into two workers is given as a number called split.

So, if the input is like blocks = [1,2], and split = 5, then the output will be 7 as we can split the worker into 2 workers in 5 time units then assign each of them to a block so the cost is 5 + maximum of 1 and 2 = 7.

To solve this, we will follow these steps −

define one priority queue pq
for initialize i := 0, when i < size of blocks, update (increase i by 1), do −
- insert blocks[i] into pq
while size of pq > 1, do −
- delete element from pq
- x := top element of pq
- delete element from pq
- insert split + x into pq
return top element of pq

Let us see the following implementation to get better understanding −

Example

Live Demo

#include <bits/stdc++.h>
using namespace std;
class Solution {
   public:
   int minBuildTime(vector<int>& blocks, int split) {
      priority_queue<int, vector<int>, greater<int> > pq;
      for (int i = 0; i < blocks.size(); i++)
      pq.push(blocks[i]);
      while (pq.size() > 1) {
         pq.pop();
         int x = pq.top();
         pq.pop();
         pq.push(split + x);
      }
      return pq.top();
   }
};
main(){
   Solution ob;
   vector<int> v = {1,2};
   cout << (ob.minBuildTime(v, 5));
}