Wandering

AtCoder

IDabc182_d

Time2000ms

Memory256MB

Difficulty—

Given is a number sequence $A_1, A_2, A_3, \dots, A_N$, which may contain negative elements. On a number line, there is a robot at coordinate $0$. It will do the following actions in order: * Move $A_1$ in the positive direction. * Move $A_1$ in the positive direction, and then move $A_2$ in the positive direction. * Move $A_1$ in the positive direction, then move $A_2$ in the positive direction, and then move $A_3$ in the positive direction. $\hspace{140pt} \vdots$ * Move $A_1$ in the positive direction, then move $A_2$ in the positive direction, then move $A_3$ in the positive direction, $\ldots$, $\dots$, and then move $A_N$ in the positive direction. Find the greatest coordinate occupied by the robot from the beginning to the end of the process. ## Constraints * $1 \le N \le 200000$ * $-10^8 \le A_i \le 10^8$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $A_1 \hspace{7pt} A_2 \hspace{7pt} A_3 \hspace{5pt} \dots \hspace{5pt} A_N$ [samples]

Samples

Input #1

3
2 -1 -2

Output #1

5

The robot moves as follows:

*   Move $2$ in the positive direction, to coordinate $2$.
*   Move $2$ in the positive direction, to coordinate $4$. Then move $-1$ in the positive direction, to coordinate $3$.
*   Move $2$ in the positive direction, to coordinate $5$. Then move $-1$ in the positive direction, to coordinate $4$. Then move $-2$ in the positive direction, to coordinate $2$.

The greatest coordinate occupied during the process is $5$, so we should print $5$.

Input #2

5
-2 1 3 -1 -1

Output #2

Input #3

5
-1000 -1000 -1000 -1000 -1000

Output #3

0

In this case, the initial coordinate $0$ is the greatest coordinate occupied.

API Response (JSON)

{
  "problem": {
    "name": "Wandering",
    "description": {
      "content": "Given is a number sequence $A_1, A_2, A_3, \\dots, A_N$, which may contain negative elements.   On a number line, there is a robot at coordinate $0$. It will do the following actions in order: *   Mov",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc182_d"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "Given is a number sequence $A_1, A_2, A_3, \\dots, A_N$, which may contain negative elements.  \nOn a number line, there is a robot at coordinate $0$. It will do the following actions in order:\n\n*   Mov...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments