https://www.codingame.com/ide/puzzle/apple-tree

apple-tree.cpp

#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

/**
 * Auto-generated code below aims at helping you parse
 * the standard input according to the problem statement.
 **/
 
struct Apple {
    int x, y, z;
    long long r;
};

bool hasCollide(Apple tmp, Apple b) {
    int x = tmp.x - b.x, y = tmp.y - b.y, r = tmp.r + b.r;
    return ((x*x + y*y) < r*r) && tmp.z > b.z;
}

void debugApple (Apple a) {
  printf("(%d, %d, %d, %lld)", a.x, a.y, a.z, a.r);
}

int main()
{
    int N, index, s_cnt;
    Apple apples[100], stack[100];
    cin >> N >> index;
    for (int i = 0; i < N; i++) {
        int x, y, z;
        long long r;
        cin >> x >> y >> z >> r;
        apples[i] = {x, y, z, r};
    }

    s_cnt = 1;
    stack[0] = apples[index];
    apples[index] = apples[--N];
    //debugApple(stack[0]);
    
    while(s_cnt > 0) {
        Apple tmp = stack[--s_cnt];
        for (int i=0; i<N; i++)
            if (hasCollide(tmp, apples[i])) {
                stack[s_cnt++] = apples[i];
                apples[i--] = apples[--N];
            }
    }

    cout << N << endl;
}

/*

3 0
0 0 150 7
0 10 100 7
0 -10 100 7

*/