求数组中等于给定值的最长子数组

//数组中等于给定值的最长子数组
#include <iostream>
#include <map>
#include <vector>
using namespace std;

int longest_sum_sub(const vector<int> &a,const int &aim)
{
    if(a.empty()||a.size()==0)
        return -1;
        
    map<int,int> map;//sum,pos;
    map.insert({0,-1});
    int maxLen=0;
    int curSum=0;
    for(int i=0;i<a.size();++i)
    {
        curSum+=a[i];
        if(map.find(curSum-aim)!=map.end())
            maxLen=max(maxLen,i-map.find(curSum-aim)->second);
        if(map.count(curSum)==0)
            map.insert({curSum,i});
    }
    return maxLen;
}

int main()
{
    vector<int> a{6,1,3,2,-1,1,5};
    cout<<longest_sum_sub(a,6)<<endl;
    return 0;
}