6868.Nim Game II

Time Limit: 1s Memory Limit: 512MB

There are $n$ heaps of sticks and two players who move alternately. On each move, a player chooses a non-empty heap and removes $1$ , $2$ , or $3$ sticks. The player who removes the last stick wins the game.

Your task is to find out who wins if both players play optimally.

Input Format(From the terminal/stdin)

The first input line contains an integer $t$ : the number of tests. After this, $t$ test cases are described:

The first line contains an integer $n$ : the number of heaps.

The next line has $n$ integers $x_1,x_2,\ldots,x_n$ : the number of sticks in each heap.

  • $1 \le t \le 2 \cdot 10^5$
  • $1 \le n \le 2 \cdot 10^5$
  • $1 \le x_i \le 10^9$
  • the sum of all $n$ is at most $2 \cdot 10^5$

Output Format(To the terminal/stdout)

For each test case, print "first" if the first player wins the game and "second" if the second player wins the game.

Sample Input

Copy
3
4
5 7 2 5
2
4 1
3
4 4 4
 \n
 \n
 · · · \n
 \n
 · \n
 \n
 · · \n

Sample Output

Copy
first
first
second
     \n
     \n
      \n
Source: CSES, Mathematics, 1098

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