整型数组处理算法（十一）请实现一个函数：线段重叠(性能优化)。[风林火山]

请实现一个函数：线段重叠; 
输入多个一维线段,求出这些线段相交的所有区域(也用线段表示);  
一条线段用两个值表示(x0,x1), 其中x1>x0;  
比如：输入线段数组[(2,4),(1.5,6),(0.5,3.5),(5,7),(7.5,9)], 
输出线段数组[(1.5,4),(5,6)]

实现如下：

//线段点信息
struct T_LineMsg
{
	int nCount;	//个数
	float fx;	//值
	T_LineMsg()
	{
		nCount = 0;
	}
};


float** GetSegmentOverlap(float** array, int nCount,int& OutCount)
{
	int i;

	vector<T_LineMsg*> vecX0;
	vector<T_LineMsg*> vecX1;

	vector<T_LineMsg> vecXAll;

	float* tempX0 = new float[nCount];//保存X0
	float* tempX1 = new float[nCount];//保存X1

	int nRet = 0;  

	memset(tempX0, 0, nCount *sizeof(float));
	memset(tempX1, 0, nCount *sizeof(float));

	int nTotalData0 =0;
	int nTotalData1 =0;
	for (i = 0; i < nCount; i++) 
	{  		
		T_LineMsg TempAll;
		TempAll.fx = array[i][0];
		vecXAll.push_back(TempAll);

		TempAll.fx = array[i][1];
		vecXAll.push_back(TempAll);

		T_LineMsg* tempX0 = new T_LineMsg;
		tempX0->fx = array[i][0];

		vecX0.push_back(tempX0);

		T_LineMsg* tempX1 = new T_LineMsg;
		tempX1->fx = array[i][1];
		vecX1.push_back(tempX1);
	}

	nTotalData0 = vecX0.size();
	nTotalData1 = vecX1.size();

	for (i=0; i< vecXAll.size(); i++)
	{
		cout << vecXAll[i].fx << ",";
	}
	cout << endl;

/*
	for (i=0; i< nTotalData0; i++)
	{
		cout << vecX0[i]->fx << ",";
	}
	cout << endl;

	for (i=0; i< nTotalData1; i++)
	{
		cout << vecX1[i]->fx << ",";
	}
	cout << endl;
*/

	float x0 = 0.0;  
	float x1 = 0.0;  
	int kk;

	//统计各值在线段区间里出现的次数
	for (i = 0; i < nCount; i++) 
	{  
		x0 = array[i][0];  
		x1 = array[i][1];

		//cout << x0 << ", " << x1 << endl;
		for (kk = 0; kk < nTotalData0; kk++)
		{  
			if (vecX0[kk]->fx > x0 && vecX0[kk]->fx < x1)
			{
				++vecX0[kk]->nCount;
			}
		}

		for (kk = 0; kk < nTotalData1; kk++) 
		{  
			if (vecX1[kk]->fx > x0 && vecX1[kk]->fx < x1)
			{
				++vecX1[kk]->nCount;
			}
		}
	} 

	nTotalData0 =1;
	nTotalData1 =1;
	//保存X0
	std::vector<T_LineMsg*>::iterator IterX0;
	for(IterX0=vecX0.begin(); IterX0!=vecX0.end(); IterX0++)
	{
		T_LineMsg* temp = *IterX0;

		if (temp->nCount== 1)
		{
			nRet = InsertData(tempX0, temp->fx, nTotalData0);
			if (nRet>0)  nTotalData0++;
		}

		delete temp;
		temp = NULL;
	}

	vecX0.clear();

	//保存X1
	std::vector<T_LineMsg*>::iterator IterX1;
	for(IterX1=vecX1.begin(); IterX1!=vecX1.end(); IterX1++)
	{
		T_LineMsg* temp = *IterX1;
		
		if (temp->nCount == 1)
		{
			nRet = InsertData(tempX1, temp->fx, nTotalData1);
			if (nRet>0)  nTotalData1++;
		}
		
		delete temp;
		temp = NULL;
	}

	vecX1.clear();
	
	OutCount = nTotalData0-1;

	float lastX1;

	if (OutCount > 0)
	{
		float** result = new float* [OutCount];
		for (int m=0; m<OutCount; m++)
		{
			result[m] = new float[2];
		}

		kk = 0;
		for (i=nTotalData0-2; i>=0; i--)
		{			
			if (kk > 0)
				lastX1 = result[kk-1][1];

			//处理(5,5.5),(5.5,6)的情况
			if (tempX0[i] == lastX1)
			{
				result[kk-1][1] = tempX1[i];
				delete result[OutCount-1];
				OutCount--;
			}
			else
			{
				result[kk][0] = tempX0[i];
				result[kk][1] = tempX1[i];	
			}

			kk++;
		}

		delete[] tempX0;
		tempX0=NULL;
		delete[] tempX1;
		tempX1=NULL;

		return result;
	}
	else
	{
		delete[] tempX0;
		tempX0=NULL;
		delete[] tempX1;
		tempX1=NULL;

		return NULL;
	}
}

/*按降序排列数组*/
int InsertData(float* a, float nValue, int nCount)
{
	int nRet = 0;
	for (int i=0; i<nCount; i++)
	{
		if (a[i]<nValue)
		{
			for (int j=nCount-1; j>i; j--)
			{
				a[j]=a[j-1];
			}
			
			a[i]=nValue;
			nRet = 1;
			
			break;//跳出循环
		}
		else if(a[i] == nValue)
		{
			break;//跳出循环
		}
	}

	return nRet;
}

有兴趣的朋友可以自己测试一下，仅供参考。

转载请注明原创链接：http://blog.csdn.net/wujunokay/article/details/12623871