[算法练习]序列最大和

题目说明：

输入一个数列（包含正负数），求和是最大的连续子序列。例如{5,-3,4,2}的最大子序列就是 {5,-3,4,2}。

 

程序代码：

#include <gtest/gtest.h>
using namespace std;

int MaxSumOfSequence(int* pData, int nLength, int& nBegin, int& nEnd)
{
    if (!pData || !nLength)
    {
        return 0;
    }

    int nMaxSum = 0;
    int nCurrVal = 0;
    int nCurrBegin = 0;

    for (int i = 0; i < nLength; ++i)
    {
        nCurrVal += pData[i];
        if (nCurrVal >= nMaxSum)
        {
            nMaxSum = nCurrVal;
            nBegin = nCurrBegin;
            nEnd = i;
        }

        if (nCurrVal < 0)
        {            
            nCurrVal = 0;
            nCurrBegin = i+1;
        }
    }

    return nMaxSum;
}

TEST(Algo, tMaxSumOfSequence)
{
    //     
    // 5,-6,4,2    
    // 5,-4,4,2    
    // 5,4,-10,2    
    
    int Data1[] = {5,-6,4,2};
    int nBegin = 0;
    int nEnd = 0;

    ASSERT_EQ(MaxSumOfSequence(Data1,4,nBegin,nEnd),6);
    ASSERT_TRUE(nBegin==2 && nEnd==3);

    int Data2[] = {5,-4,4,2};
    ASSERT_EQ(MaxSumOfSequence(Data2,4,nBegin,nEnd),7);
    ASSERT_TRUE(nBegin==0 && nEnd==3);

    int Data3[] = {5,4,-10,2};
    ASSERT_EQ(MaxSumOfSequence(Data3,4,nBegin,nEnd),9);
    ASSERT_TRUE(nBegin==0 && nEnd==1);
}