Codeforces 379B New Year Present(模拟)

题目链接：Codeforces 379B New Year Present

模拟。

维持一个sum值表示所有初始ai的和，然后从左向右走，再从右往左走，途中根据ai值更新sum值和ai值，直到sum = 0，退出while。

#include <iostream>

using namespace std;

const int MAX_N = 300 + 50;
int arr[MAX_N];
int n;

int main()
{
    while(cin >> n)
    {
        int sum = 0;
        for(int i = 1;i <= n;i++)
        {
            cin >> arr[i];
            sum += arr[i];
        }
        int i = 1;
        int dir = 1;
        while(true)
        {
            if(dir == 1)// go to the right
            {
                if(arr[i] > 0)
                {
                    cout << "P";

                    arr[i]--;
                    sum--;
                    if(sum == 0)
                        break;
                    if(i == n)
                    {
                        cout << "L";
                        i--;
                        dir = 0;
                    }
                    else
                    {
                        cout << "R";
                        i++;
                    }

                }
                else if(arr[i] == 0)
                {
                    if(i == n)
                    {
                        cout << "L";
                        i--;
                        dir = 0;
                    }
                    else
                    {
                        cout << "R";
                        i++;
                    }
                }
            }
            else //go to the left
            {
                if(arr[i] > 0)
                {
                    cout << "P";
                    arr[i]--;
                    sum--;
                    if(sum == 0)
                        break;
                    if(i == 1)
                    {
                       dir = 1;
                       cout << "R";
                       i++;
                    }
                    else
                    {
                        cout << "L";
                        i--;
                    }

                }
                else if(arr[i] == 0)
                {
                    if(i == 1)
                    {
                       dir = 1;
                       cout << "R";
                       i++;
                    }
                    else
                    {
                        cout << "L";
                        i--;
                    }
                }
            }
        }
        cout << endl;

    }
    return 0;
}