Problem G
Hill Climbing
SoCCat the Hill Climber is a very determined cat. Currently, SoCCat is climbing the hill of an NP-hard problem!
Everyone knows that the graph edge partitioning problem is NP-hard. As there are many variants of it, here’s the one that SoCCat is talking about:
There is a connected graph with $n$ vertices and $m$ edges. You can color each edge into $m$ possible colors, numbered from $1$ to $m$. However, you can only color at most $a_ c$ edges with color $c$.
A coloring of a subset of edges is valid if it satisfies all of the following conditions for each color $1 \leq c \leq m$:
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There are at most $a_ c$ edges with color $c$.
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Every pair of edges with color $c$ is reachable from each other by only using edges with color $c$. In other words, if $V_ c$ is the set of all vertices adjacent to an edge with color $c$, and $E_ c$ is the set of all edges with color $c$, then the subgraph $(V_ c, E_ c)$ is connected.
Note that you can leave some edges uncolored. Uncolored edges do not have to satisfy any of the above conditions.
SoCCat is confident that their hill-climbing algorithm can correctly determine whether a valid coloring with at least $\lceil \frac{n}{2} \rceil $ colored edges exist with $99.8244353\% $ probability.
SoCCat does not believe you could match their algorithm’s performance in a mere $4$ hours. After all, SoCCat took weeks to design and code a very efficient and robust hill-climbing algorithm to do this task.
Can you do it?
Input
The input starts with a line containing an integer $C$, denoting the number of test cases ($1 \leq C \leq 300\, 000$). Each test case has the following format.
The first line contains two integers $n$ and $m$, denoting the number of vertices and the number of edges in the graph, respectively ($2 \leq n \leq 300\, 000$; $n - 1 \leq m \leq 300\, 000$). The sum of $n$ and $m$ over all test cases does not exceed $300\, 000$.
The second line contains $m$ space-separated integers $a_1, a_2, \ldots , a_ m$, where $a_ i$ denotes the maximum number of edges you can color with color $i$ ($0 \leq a_ i \leq m$; $\sum _ i a_ i \leq m$).
The following $m$ lines each contain two integers $u$ and $v$, denoting an edge between vertices $u$ and $v$ ($1 \leq u, v \leq n$). The graph is guaranteed to be connected and has no self-loops or multiple edges.
Output
For each test case, output Yes if there exists a valid coloring with at least $\lceil \frac{n}{2} \rceil $ colored edges, and No otherwise.
Additionally, if the answer is Yes, output a line containing $m$ space-separated integers $c_1, c_2, \ldots , c_ m$. $c_ i$ should be equal to the color of the $i$-th edge, or $0$ if the $i$-th edge is uncolored ($0 \leq c_ i \leq m$).
There should be at least $\lceil \frac{n}{2} \rceil $ colored edges, and the coloring should be valid. If there are multiple possible answers, output any one of them.
Sample Input 1 | Sample Output 1 |
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4 5 4 4 0 0 0 2 3 2 1 4 5 4 3 6 11 0 0 0 0 0 0 0 3 2 3 3 1 2 2 3 3 4 4 5 5 6 6 1 1 4 4 2 2 5 5 3 4 6 6 11 0 0 0 0 0 0 0 3 2 3 3 1 2 2 3 3 4 4 5 5 6 6 1 1 4 4 2 2 5 5 3 4 6 5 10 1 0 0 0 0 0 0 0 0 1 1 2 2 3 3 4 4 5 5 1 1 3 3 5 5 2 2 4 4 1 |
Yes 1 1 0 1 Yes 8 11 10 10 9 8 8 11 9 10 11 Yes 11 11 11 0 0 0 0 0 0 0 0 No |