Codeforces Round 818 (Div. 2)
F
Madoka and The First Session
Codeforces
2500
原题
← E→
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Oh no, on the first exam Madoka got this hard problem:

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Given integer $n$ and $m$ pairs of integers ($v_i, u_i$). Also there is an array $b_1, b_2, \ldots, b_n$, initially filled with zeros.

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Then for each index $i$, where $1 \leq i \leq m$, perform either $b_{v_i} := b_{v_i} - 1$ and $b_{u_i} := b_{u_i} + 1$, or $b_{v_i} := b_{v_i} + 1$ and $b_{u_i} := b_{u_i} - 1$. Note that exactly one of these operations should be performed for every $i$.

翻译中…

Also there is an array $s$ of length $n$ consisting of $0$ and $1$. And there is an array $a_1, a_2, \ldots, a_n$, where it is guaranteed, that if $s_i = 0$ holds, then $a_i = 0$.

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Help Madoka and determine whenever it is possible to perform operations in such way that for every $i$, where $s_i = 1$ it holds that $a_i = b_i$. If it possible you should also provide Madoka with a way to perform operations.

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Input

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The first line contains two integers $n$ and $m$ ($2 \leq n \leq 10000, 1 \leq m \leq 10000$) — the length of the array $a$ and the number of pair of integers.

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The second line contains $n$ integers $s_1, s_2, \ldots s_n$ ($0 \le s_i \le 1$) — the elements of the array $s$.

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The third line contains $n$ integers $a_1, a_2, \ldots, a_n$ ($|a_i| \leq m$) — the elements of the array $a$. It is guaranteed that if $s_i = 0$ holds, then $a_i = 0$.

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$i$-th of the following $m$ lines contains two integers $v_i$ and $u_i$ ($1 \leq v_i, u_i \leq n, v_i \ne u_i$) — the indexes of the elements of the array $b$ to which the operation is performed. It is also guaranteed that there are no two indices $i$ and $j$, where $1 \le i \lt j \le m$, such that $(v_i, u_i) = (v_j, u_j)$ or $(v_i, u_i) = (u_j, v_j)$.

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Output

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In the first line print "YES" if it is possible to perform operations in the required way, and "NO" otherwise.

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You may print each letter in any case (for example, "YES", "Yes", "yes", "yEs" will all be recognized as positive answer).

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In case you printed "YES", print $m$ pairs of integers. If for pair $(v_i, u_i)$ we should perform $b_{v_i} := b_{v_i} - 1$ and $b_{u_i} := b_{u_i} + 1$, print $(v_i, u_i)$. Otherwise print $(u_i, v_i)$. If there are multiple ways to get the correct answer, you can print any of them.

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You can print pairs in any order.

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Note

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In the first example, the array $b$ will change as follows: $[0,0,0,0,0] \rightarrow [-1,0,0,1,0] \rightarrow [-2,0,0,1,1] \rightarrow [-2,0,1,0,1] \rightarrow [-2,0,2,0,0] \rightarrow [-2,0,2,1,-1]$. $a_i = b_i$ for all indices $i$ from $1$ to $5$.

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In the second example, it is enough for us that $b_2 = 1$ at the end, since only $s_2 = 1$.

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In the third example, the operations cannot be performed as required.

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样例

Input #1
5 5
1 1 1 1 1
-2 0 2 1 -1
1 5
1 4
3 5
3 4
4 5
Output #1
YES
1 5
1 4
5 3
4 3
5 4
InputCopy OutputCopy
Input #2
5 5
0 1 0 1 0
0 1 0 0 0
1 3
2 3
3 5
3 4
4 5
Output #2
YES
3 1
3 2
5 3
3 4
4 5
InputCopy OutputCopy
Input #3
4 4
1 1 1 1
0 2 -2 2
1 3
1 4
2 3
2 4
Output #3
NO
InputCopy OutputCopy
题目信息
题号
1717F
时间限制
2 s
内存限制
256 MB
标签
构造
网络流
图匹配
图论
模拟

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