二分搜索查找左侧边界
import java.util.*; public class Solution { public int search (int[] nums, int target) { int left = 0,right = nums.length-1; while(left<=right){ int mid = left + (right - left)/2; if(nums[mid] == target){ right = mid-1; }else if(nums[mid] < target){ left = mid+1; }else if(nums[mid] > target){ right = mid-1; } } if(left == nums.length){ return -1; } return nums[left] == target ? left:-1; } }