剑指offer编程题（JAVA实现)——第37题：数字在排序数组中出现的次数

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github	https://github.com/JasonZhangCauc/JZOffer

• 剑指offer编程题（JAVA实现)——第37题：数字在排序数组中出现的次数
• 题目描述
• 统计一个数字在排序数组中出现的次数。

public class Test37 {
	public static void main(String[] args) {
		int[] array = { 1, 2, 3, 4, 5, 5, 5 };
		System.out.println(GetNumberOfK(array, 5));
	}

	public static int GetNumberOfK(int[] array, int k) {
		int count = 0;
		for (int i = 0; i < array.length; i++) {
			if (array[i] == k) {
				for (int j = i; j < array.length; j++) {
					if (array[j] == k) {
						count++;
					} else {
						break;
					}
				}
				break;
			}
		}
		return count;
	}
}
//二分方法
/**
public class Solution {
    public int GetNumberOfK(int [] array , int k) {
        int length = array.length;
        if(length == 0){
            return 0;
        }
        int firstK = getFirstK(array, k, 0, length-1);
        int lastK = getLastK(array, k, 0, length-1);
        if(firstK != -1 && lastK != -1){
             return lastK - firstK + 1;
        }
        return 0;
    }
    //递归写法
    private int getFirstK(int [] array , int k, int start, int end){
        if(start > end){
            return -1;
        }
        int mid = (start + end) >> 1;
        if(array[mid] > k){
            return getFirstK(array, k, start, mid-1);
        }else if (array[mid] < k){
            return getFirstK(array, k, mid+1, end);
        }else if(mid-1 >=0 && array[mid-1] == k){
            return getFirstK(array, k, start, mid-1);
        }else{
            return mid;
        }
    }
    //循环写法
    private int getLastK(int [] array , int k, int start, int end){
        int length = array.length;
        int mid = (start + end) >> 1;
        while(start <= end){
            if(array[mid] > k){
                end = mid-1;
            }else if(array[mid] < k){
                start = mid+1;
            }else if(mid+1 < length && array[mid+1] == k){
                start = mid+1;
            }else{
                return mid;
            }
            mid = (start + end) >> 1;
        }
        return -1;
    }
}
*/