A9611. 24 Game
编程题
普及/提高-
知识点
题目描述
Little X used to play a card game called "24 Game", but recently he has found it too easy. So he invented a new game.
Initially you have a sequence of $n$ integers: $1,2,...,n$ . In a single step, you can pick two of them, let's denote them $a$ and $b$ , erase them from the sequence, and append to the sequence either $a+b$ , or $a-b$ , or $a×b$ .
After $n-1$ steps there is only one number left. Can you make this number equal to $24$ ?
Initially you have a sequence of $n$ integers: $1,2,...,n$ . In a single step, you can pick two of them, let's denote them $a$ and $b$ , erase them from the sequence, and append to the sequence either $a+b$ , or $a-b$ , or $a×b$ .
After $n-1$ steps there is only one number left. Can you make this number equal to $24$ ?
输入格式
The first line contains a single integer $n$ $(1<=n<=10^{5})$ .
输出格式
If it's possible, print "YES" in the first line. Otherwise, print "NO" (without the quotes).
If there is a way to obtain $24$ as the result number, in the following $n-1$ lines print the required operations an operation per line. Each operation should be in form: " $a$ $op$ $b$ = $c$ ". Where $a$ and $b$ are the numbers you've picked at this operation; $op$ is either "+", or "-", or "\*"; $c$ is the result of corresponding operation. Note, that the absolute value of $c$ mustn't be greater than $10^{18}$ . The result of the last operation must be equal to $24$ . Separate operator sign and equality sign from numbers with spaces.
If there are multiple valid answers, you may print any of them.
If there is a way to obtain $24$ as the result number, in the following $n-1$ lines print the required operations an operation per line. Each operation should be in form: " $a$ $op$ $b$ = $c$ ". Where $a$ and $b$ are the numbers you've picked at this operation; $op$ is either "+", or "-", or "\*"; $c$ is the result of corresponding operation. Note, that the absolute value of $c$ mustn't be greater than $10^{18}$ . The result of the last operation must be equal to $24$ . Separate operator sign and equality sign from numbers with spaces.
If there are multiple valid answers, you may print any of them.
输入输出样例
输入 #1
1
输出 #1
NO
输入 #2
8
输出 #2
YES 8 * 7 = 56 6 * 5 = 30 3 - 4 = -1 1 - 2 = -1 30 - -1 = 31 56 - 31 = 25 25 + -1 = 24