最大子序列和问题

包括两个方法，分治法与最优起点法。生成随机数写入文件，从文件读取数据，求出最大子序列和并且把子序列输出到文件中
还有两个算法运行的时间。#include <iostream>
#include <fstream>
#include <vector>
#include <time.h>
#define length 5
using namespace std;
int max3(int a,int b,int c){
if(a>b)
return a>c?a:c;
else
return b>c?b:c;
}

int maxSubArray(int a[],int l,int r){
if(r==l)
return a[l];

int mid=(r+l)/2;
int maxLeftSum=maxSubArray(a,l,mid);
int maxRightSum=maxSubArray(a,mid+1,r);

int maxLeftBorderSum=0,leftBorderSum=0;
for(int i=mid;i>=l;i--){
leftBorderSum+=a[i];
if(maxLeftBorderSum<leftBorderSum)
maxLeftBorderSum=leftBorderSum;
}

int maxRightBorderSum=0,rightBorderSum=0;
for(int i=mid+1;i<=r;i++){
rightBorderSum+=a[i];
if(rightBorderSum>maxRightBorderSum)
maxRightBorderSum=rightBorderSum;
}

return max3(maxRightSum,maxLeftSum,maxRightBorderSum+maxLeftBorderSum);

}

int e=0,b=0;
int a[length];
std::vector<int> s{0};
int maxSubArray2(int a[],int size){
int sum=0,maxSum=0;
for(int i=0;i<size;i++){
sum+=a[i];
// cout<<a[i]<<" "<< sum<<endl;

if(maxSum<sum) {
maxSum = sum;
e=i;
}
else if(sum<0){
s.push_back(i+1);
sum=0;
}
}
return maxSum;
}

int main() {
//std::cout << "Hello, World!" << std::endl;
srand((unsigned)time(NULL));
clock_t start1,start2,end1,end2;
int maxSum=0;
ofstream otf;
otf.open("input.txt");
for(int i=0;i<length;i++)
otf << random() % 10 - 4 << " ";
otf.close();

ifstream itf("/Users/meser/Documents/AlgorithmTest/test1/cmake-build-debug/input.txt");
for(int i=0;i<length;i++) {
itf >> a[i];
//cout<<a[i]<<" ";
}
itf.close();
start1=clock();
int result=maxSubArray(a,0,length-1);
end1=clock();
cout<<result<<" 运行时间为 "<<end1-start1<<endl;
start2=clock();
int result1=maxSubArray2(a,length);
end2=clock();
cout<<result1<<" 运行时间为 "<<end2-start2<<endl;

for(int i=0;i<s.size();i++)
if(s[i]<=e)
b=s[i];
//for(int i=b;i<=e;i++)
// maxSum+=a[i];
// cout<<maxSum<<endl;
otf.open("output.txt");
for(int i=b;i<=e;i++){
otf<<a[i]<<" ";
}
otf.close();

return 0;
}