题目描述
统计一个数字在升序数组中出现的次数。
示例 1
输入
[1,2,3,3,3,3,4,5],3
返回值
4
核心代码实现
public class Solution {
public int GetNumberOfK(int [] array , int k) {
if(array == null || array.length == 0){
return 0;
}
int counts = 0;
/*方法一
for(int i = 0; i < array.length; i++){
if(k == array[i]){
counts++;
}
}
return counts;
*/
//方法二:二分法
int low = 0, mid = 0, high = array.length - 1;
while(low < high){
mid = low + (high - low)/2;
if(array[mid] < k){
low = mid + 1;
}else if(array[mid] > k){
high = mid - 1;
}else{
break;
}
}
for(int i = low; i <= high; i++){
if(array[i] == k){
counts++;
}
}
return counts;
}
}