【CF＃223 (Div. 2)】A. Sereja and Dima

Through the tunnel

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The question ： Put the cards in a row on the table ,S and D Two candidate cards （ Only the leftmost and rightmost cards can be selected ）, To maximize their total points .
The cards on the table are gone , Then the game is over .
S For the first time

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Ideas ： simulation , Double pointer , greedy .
Locate the left and right ends of the array , The double pointer moves to the middle , Know that double pointers point to the same element , At the same time, judge whose turn it is to touch the cards .

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#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e5 + 10;
int n,t,m;
int a[N],b[N],c[N];
bool vis[N];
int main(){
    
	cin >> n;
	int u = n;
	int s = 0, d = 0;
	for(int i = 0; i < n; i++){
    
		cin >> a[i];
	}
	int i = 0, j = n - 1, flag = 1;
	while(i != j){
    
		if(a[i] > a[j]){
    
			if(flag == 1){
    
				s += a[i];
				flag = 0;
			}
			else{
    
				d += a[i];
				flag = 1;
			}
			i++;
		}
		else{
    
			if(flag == 1){
    
				s += a[j];
				flag = 0;
			}
			else{
    
				d += a[j];
				flag = 1;
			}
			j--;
		}
		u--;
	}
	if(flag == 1){
    
		s += a[i];
	}
	else{
    
		d += a[i];
	}
	cout << s << " " << d << endl;
	return 0;
}