剑指Offer-面试题3 数组中重复的数字

//剑指Offer第三题
//哈工大周兴
//联系：qq960020310
#include <iostream>

using namespace std;

/*
//插入排序
bool insertSort(int *a,int len)
{
if (a==nullptr)
{
return false;
}
for (int i=0;i<len;i++)
{
for (int j = 0;j <i;j++)
{
if (j==0 && a[i]<a[j])
{
int temp = a[j];
a[j] = a[i];
a[i] = temp;
break;
}
if (j>=0 && j<i-1)
{
if (a[i]>=a[j] && a[i]<a[j+1])
{
int temp = a[i];
for (int k=i;k>j+1;k--)
{
a[k] = a[k - 1];
}
a[j + 1] = temp;
break;
}
}
}
}

return true;
}

bool findNumber(int a[], int len)
{
if (a==nullptr)
{
return false;
}
int i = 0;
while (i<len-1)
{
int k=i;
if (a[i]==a[i+1])
{
int count = 2;
k = i+1;
while (k+1<len && a[k]==a[k+1])
{
count++;
k++;
}
printf("数字%d重复了%d次！", a[i], count);
}

i = k;
i++;
}

return true;
}
*/

/*
	bool duplicate(int numbers[], int length, int *duplication)
{
	int count = 0;
	if (numbers==nullptr ||length<0)
	{
		return false;
	}

	for (int i=0;i<length;i++)
	{
		if (numbers[i]<0 || numbers[i]>length-1)
		{
			return false;
		}
	}

	for (int i=0;i<length;i++)
	{
		while (numbers[i]!=i)
		{
			if (numbers[i]==numbers[numbers[i]])
			{
				*duplication = numbers[i];
				return true;
			}

			int temp = numbers[i];
			numbers[i] = numbers[temp];
			numbers[temp] = temp;
			cout << count++ << endl;
		}
	}

	return false;
}
*/
//类似二分查找，不修改原数组
int getDuplication(const int number[], int length)
{
	if (number==nullptr || length<=0)
	{
		return -1;
	}
	int head = 1;
	int rear = length - 1;
	int div = (length-1)>>1;
	cout << "head= " << head << endl;
	cout << "rear= " << rear << endl;
	cout << "div= " << div << endl;
	while (!(div==head && div==rear))
	{
		cout << "进来了！" << endl;
		int upDiv = 0;
		int downDiv = 0;
		for (int i=0;i<length;i++)
		{
			if (number[i]>div && number[i]<=rear)
			{
				upDiv++;
			}
			if (number[i]>=head && number[i]<=div)
			{
				downDiv++;
			}
		}
		cout << "updiv: " << upDiv << endl;
		cout << "downdiv: " << downDiv << endl;
		if (downDiv>(div-head+1))
		{
			rear = div;
			div = (div+head)>>1;
		}
		else
		{
			head = div + 1;
			div = (div + 1 + rear) >>1;
		}
	}

	return div;
}

int main(void)
{
	int a[9] = {1,4,3,5,3,4,6,4,2};
	int dup=getDuplication(a, 9);

	cout << dup << endl;
	system("pause");
	return 0;
}