public class Solution {
public int GetNumberOfK(int[] array, int k) {
int left = findFirstK(array, 0, array.length-1, k);
int right = findLastK(array, 0, array.length-1, k);
if(left==-1||right==-1){
return 0;
}else{
return right-left+1;
}
}
private int findFirstK(int[] array, int left, int right, int k){
if(left>right){
return -1;
}else if(left==right && array[left]==k){
return left;
}
int mid = (left+right)/2;
if(array[mid]==k) {
if ((mid > 0 && array[mid - 1] != k) || mid == 0) {
return mid;
}
right = mid - 1;
}else if(array[mid]<k){
left = mid+1;
}else{
right = mid-1;
}
return findFirstK(array, left, right, k);
}
private int findLastK(int[] array, int left, int right, int k){
if(left>right){
return -1;
}else if(left==right && array[left]==k){
return left;
}
int mid = (left+right)/2;
if(array[mid]==k) {
if ((mid < array.length-1 && array[mid + 1] != k) || mid == array.length-1) {
return mid;
}
left = mid + 1;
}else if(array[mid]<k){
left = mid+1;
}else{
right = mid-1;
}
return findLastK(array, left, right, k);
}
}
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