二分查找

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17

a := []int{0, 1, 2, 3, 4, 5, 6}

func binarySearch(array []int, target int) (bool, int) {
	min := 0
	max := len(array) - 1
	for min <= max {
		mid := (max-min)/2 + min
		if target > array[mid] {
			min = mid + 1
		} else if target < array[mid] {
			max = mid - 1
		} else {
			return true,target
		}
	}
	return false,0
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

public class BinarySearch {
  public static void main(String[] args) {
      ArrayList<Integer> list = new ArrayList<>();
      list.add(0);
      list.add(1);
      list.add(2);
      list.add(3);
      list.add(4);
      list.add(5);
      list.add(6);
      System.out.println(binarySearch(list, 9));
  }

  public static <E extends Comparable<E>> E binarySearch(ArrayList<E> list, E target) {
      if (list == null || target == null) return null;
      var min = 0;
      var max = list.size() - 1;
      while (min <= max) {
          var mid = min + (max - min) / 2;
          if (target.compareTo(list.get(mid)) > 0) {
              min = mid + 1;
          } else if (target.compareTo(list.get(mid)) == 0) {
              return target;
          } else {
              max = mid - 1;
          }
      }
      return null;
  }
}