最大子列和 分治算法与在线处理算法

刚做完题，先把代码放着，有时间在更新
分治算法

#include <iostream>

using namespace std;

#define  maxn (int)10e5+5
int array[maxn]={0};
int main()
{
    int n;
    int i;
    int len;
    cin>>len;
    for(i=0;i<len;++i)
        cin>>array[i];
    int maxsubsequence_binary(int * ,int left ,int right);
    int ans =max(0,maxsubsequence_binary(array,0,len));
    cout<<ans<<endl;
}

int maxsubsequence_binary(int *array,int left,int right)
{
    int subans=0;
    if (left==right)
        return max(array[left],0);
    int mid=(left+right)/2;
    int maxleft=maxsubsequence_binary(array,left,mid);
    int maxright= maxsubsequence_binary(array,mid+1,right);

    int leftBorderSum(0),rightBoderSum(0);
    int maxleftBorderSum(0),maxRightBorderSum(0);

    int i;
    for(i=mid;i>=left;--i)
    {
        leftBorderSum+=array[i];
        maxleftBorderSum=max(maxleftBorderSum,leftBorderSum);
    }

    for(i=mid+1;i<right;++i)
    {
       rightBoderSum+=array[i];
       maxRightBorderSum=max(maxRightBorderSum,rightBoderSum);
    }
    int temp=max(maxleft,maxright);
    if(temp>maxleftBorderSum+maxRightBorderSum)
        return temp;
    else
        return maxleftBorderSum+maxRightBorderSum;

}

在线处理算法

int maxSubsequence_online(int* array,int length )
{
    int thisSum(0),maxSum(0);
    int i;
    for (i=0;i<length;++i)
    {
        thisSum=max(thisSum+array[i],0);
        maxSum=max(maxSum,thisSum);
    }
    return  maxSum;
}