Find Positive Integer Solution for a Given Equation LeetCode solution in Java

1
class Solution {
2
  private int binarySearch(int ans, int x, CustomFunction func) {
3
    int left = 1, right = 1000;
4
    while (left <= right) {
5
      int mid = left + (right - left) / 2;
6

7
      int res = func.f(x, mid);
8

9
      if (res == ans) {
10
        return mid;
11
      }
12
      if (res < ans) {
13
        left = mid + 1;
14
      } else {
15
        right = mid - 1;
16
      }
17
    }
18
    return -1;
19
  }
20

21
  public List<List<Integer>> findSolution(CustomFunction customfunction, int z) {
22
    List<List<Integer>> res = new ArrayList<>();
23

24
    for (int i = 1; i <= 1000; i++) {
25
      int ans = binarySearch(z, i, customfunction);
26
      if (ans != -1) {
27
        List<Integer> temp = new ArrayList<>();
28
        temp.add(i);
29
        temp.add(ans);
30
        res.add(temp);
31
      }
32
      if (customfunction.f(i, 1) > z) {
33
        break;
34
      }
35
    }
36
    return res;
37
  }
38
}