有序正负数组最近0的两个数

保证数组有正负数。

解法：二分查找+最小的两个数

public class Solution {
  public int[] closed0TwoNum(int[] a) {
    // 找最接近0的非负数
    int i = binarySearch(a, 0);

    // 添加候选集
    List<Integer> candidates = new ArrayList<>();
    candidates.add(a[i]);
    candidates.add(a[i-1]);
    if (i + 1 < a.length) candidates.add(a[i+1]);
    if (i - 2 >= 0) candidates.add(a[i-2]);

    // 找绝对值最小的两个数
    int closed0 = Integer.MAX_VALUE, secClosed0 = Integer.MAX_VALUE;
    for (int e : candidates) {
      int absE = Math.abs(e);
      int absClosed0 = Math.abs(closed0);
      int absSecClosed0 = Math.abs(secClosed0);
      if (absE < absClosed0) {
        secClosed0 = closed0;
        closed0 = e;
      } else if (absE < absSecClosed0) {
        secClosed0 = e;
      }
    }
    return new int[]{closed0, secClosed0};
  }

  // 二分查找大于等于target的最小值
  private int binarySearch(int[] a, int target) {
    int low = 0, high = a.length - 1;
    while (low <= high) {
      int mid = (low + high) >>> 1;
      if (a[mid] > target) high = mid - 1;
      else if (a[mid] < target) low = mid + 1;
      else return mid;
    }
    return low;
  }
}