binarysearch.java

来自「java初学例子」· Java 代码 · 共 33 行

public class BinarySearch {
  /** Main method */
  public static void main(String[] args) {
    int[] list = {2, 4, 7, 10, 11, 45, 50, 59, 60, 66, 69, 70, 79};

    int i = binarySearch(list, 2);
    int j = binarySearch(list, 11);
    int k = binarySearch(list, 12);

    System.out.println(i);
    System.out.println(j);
    System.out.println(k);
  }

  /** Use binary search to find the key in the list */
  public static int binarySearch(int[] list, int key) {
    int low = 0;
    int high = list.length - 1;

    while (high >= low) {
      int mid = (low + high) / 2;
      if (key < list[mid])
        high = mid - 1;
      else if (key == list[mid])
        return mid;
      else
        low = mid + 1;
    }

    return -low - 1;
  }
}