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