各位大佬，请问我哪里错了，求讲解

#include<iostream>

#include<algorithm>

using namespace std;

int main (){

int n;

cin>>n;

int nums[1000001];

for (int i=0;i<n;i++){

cin>>nums[i];

}

for (int i=1;i<n;i++){

int sum=nums[i-1]+nums[i];

if (sum>nums[i]){

nums[i]=sum;

}

}

sort(nums,nums+n);

cout<<nums[n-1]<<endl;

return 0;

}