Search for a Range
Given a sorted array of n integers, find the starting and ending position of a given target value.
If the target is not found in the array, return [-1, -1]
.
Example
Given [5, 7, 7, 8, 8, 10]
and target value 8
,
return [3, 4]
.
分析:
这道题只需要分别对起点和终点用二分查找就可以啦~
public class Solution { /** *@param A : an integer sorted array *@param target : an integer to be inserted *return : a list of length 2, [index1, index2] */ public int[] searchRange(int[] A, int target) { if (A.length == 0) { return new int[]{-1, -1}; } int[] result = new int[2]; int start, end; //search the first element start = 0; end = A.length - 1; while (start + 1 < end) { int mid = start + (end - start) / 2; if (A[mid] == target) { end = mid; } else if (A[mid] < target) { start = mid; } else { end = mid; } } if(A[start] == target) { result[0] = start; } else if (A[end] == target){ result[0] = end; } else { result[0] = result[1] = -1; return result; } //search the second element start = 0; end = A.length - 1; while (start + 1 < end) { int mid = start + (end - start) / 2; if (A[mid] == target) { start = mid; } else if (A[mid] < target) { start = mid; } else { end = mid; } } if(A[end] == target) { result[1] = end; } else if (A[start] == target){ result[1] = start; } else { result[0] = result[1] = -1; return result; } return result; } }