プログラマーマットC++池

#include <string>
#include <vector>
#include <algorithm>
using namespace std;
int solution(int distance, vector<int> rocks, int n) {
    int answer = 0;
    sort(rocks.begin(),rocks.end());
    
    int start = 0;
    int end = distance;
    while(start <= end){
        int mid = (start + end) / 2;
        int cnt = 0;
        int left = 0;
        
        for(int i=0;i<rocks.size();i++){
            if(rocks[i] - left >= mid) left = rocks[i];
            else cnt++;
        }
        
        if(cnt > n) {
            end = mid - 1;
        }
        else{
            answer = max(answer,mid);
            start = mid + 1;
        }
    }
    
    return answer;
}