数学乱搞就行了

#include<iostream>
#define ll long long
using namespace std;
ll a[1145141];
ll mount[1145141];
int main()
{
	freopen("rain.in","r",stdin);
	freopen("rain.out","w",stdout);
	ll n;cin>>n;
	ll mountain_1=0;
	for(ll i=1;i<=n;i++) cin>>a[i];
	for(ll i=1;i<=n;i++){
		if(i%2==1) mountain_1+=a[i];
		else mountain_1-=a[i];
	}
	for(ll i=1;i<=n;i++)
	{
		if(i==1) mount[1]=mountain_1;
		else mount[i]=a[i-1]*2-mount[i-1];
		cout<<mount[i]<<" ";
	}
}

数学题

#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define ld long double
#define inf 0x3f3f3f3f
#define endl '\n'

int n;
ll a[100007];
ll x[100007];

int main(){
	freopen("rain.in","r",stdin);
	freopen("rain.out","w",stdout);

	cin>>n;
	for(int i=1;i<=n;i++) cin>>a[i];
	
	ll p = 2*a[1];
	for(int i=2;i<=n;i++){
		if(i%2==0) p-=2*a[i];
		else p+=2*a[i];
	}
	p/=2; // x1
	x[1]=p;
	
	for(int i=2;i<=n;i++) x[i]=2*a[i-1]-x[i-1];
	for(int i=1;i<=n;i++) cout<<x[i]<<" ";

	return 0;
}