学步园

#include <iostream>

using namespace std;

bool FindGreatestSumOfSubArray(int *pData, unsigned int nLength, int &nGreatestSum)
{
 if (!pData||0==nLength)
 {
  return false;
 }

 int nCurrentSum=nGreatestSum=0;
 for (unsigned int i=0; i<nLength; i++)
 {
  nCurrentSum+=pData[i];

  //if the sum is negative, discard it.
  if (nCurrentSum<0)
  {
   nCurrentSum=0;
  }

  if (nCurrentSum>nGreatestSum)
  {
   nGreatestSum=nCurrentSum;
  }  
 }

 //if all data are negative, find the greatest element in array
 if (nGreatestSum==0)
 {
  nGreatestSum=pData[0];
  for (unsigned int i=1; i<nLength; ++i)    
  {
   if (pData[i]>nGreatestSum)
   {
    nGreatestSum=pData[i];
   }
  }
 }

 return true;
}

int main()
{
 int data[]={1, -2, 3, 10, -4, 7, 2, -5};
 int greatest=0;
 unsigned int length=sizeof(data)/sizeof(int);
 cout<<"length = "<<length<<endl;

 if (FindGreatestSumOfSubArray(data, length, greatest))
 {
  cout<<"the greatest sum of the sub array is: "<<greatest<<endl;
 }

 for (int i=0; i<5; i++)
 {
  cout<<i<<"\t";
 }
 cout<<endl;

 for (int j=0; j<5; ++j)
 {
  cout<<j<<"\t";
 }
 cout<<endl;

 return 0;
}