每天一道剑指offer-数字在排序数组中出现的次数 https://www.nowcoder.com/practice/70610bf967994b22bb1c26f9ae901fa2?tpId=13&tqId=11190&tPage=2&rp=2&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking
统计一个数字在排序数组中出现的次数。
思路
示例
public class Solution {
public int GetNumberOfK(int [] array , int k) {
int leftIndex = -1,start=0,end=array.length-1,rightIndex=-1;
while(start <= end)
{
int mid = (start+end)/2;
if(array[mid] > k)
{
end = mid-1;
}else if(array[mid] < k){
start = mid+1;
}else{
leftIndex = mid;
end = mid-1;
}
}
start = 0;
end = array.length-1;
while(start <= end)
{
int mid = (start+end)/2;
if(array[mid] > k)
{
end = mid-1;
}else if(array[mid] < k){
start = mid+1;
}else{
rightIndex = mid;
start = mid+1;
}
}
if(array.length == 0 || rightIndex == -1)
return 0;
return rightIndex-leftIndex+1;
}
}