public override void Solve(IOManager io)
{
const string Inf = "zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz";
var n = io.ReadInt();
var edgeCount = io.ReadInt();
var length = io.ReadInt();
var originalCharList = new char[n];
for (int i = 0; i < originalCharList.Length; i++)
{
originalCharList[i] = io.ReadChar();
}
var originalGraph = new Internal.SCCGraph(n);
var edges = new Edge[edgeCount];
for (int i = 0; i < edges.Length; i++)
{
var a = io.ReadInt();
var b = io.ReadInt();
a--;
b--;
edges[i] = new Edge(a, b);
originalGraph.AddEdge(a, b);
}
var(groupCount, ids) = originalGraph.SCCIDs();
var graph = new BasicGraph(groupCount + 1);
foreach (var(from, to) in edges)
{
if (ids[from] != ids[to])
{
var contains = false;
foreach (var next in graph[ids[from] + 1])
{
contains |= next == ids[to] + 1;
}
if (!contains)
{
graph.AddEdge(ids[from] + 1, ids[to] + 1);
}
}
}
for (int i = 1; i < graph.NodeCount; i++)
{
graph.AddEdge(0, i);
}
var dp = new string[graph.NodeCount, length + 1];
dp.Fill(Inf);
dp[0, 0] = "";
var charList = Enumerable.Repeat(0, graph.NodeCount).Select(_ => new List <char>()).ToArray();
for (int i = 0; i < originalCharList.Length; i++)
{
charList[ids[i] + 1].Add(originalCharList[i]);
}
foreach (var c in charList)
{
c.Sort();
}
for (int i = 0; i < graph.NodeCount; i++)
{
for (int l = 0; l <= length; l++)
{
foreach (var next in graph[i])
{
var newString = dp[i, l];
if (newString == Inf)
{
continue;
}
ChangeMin(ref dp[next, l], newString);
for (int append = 0; append < charList[next].Count; append++)
{
newString += charList[next][append];
if (newString.Length <= length)
{
ChangeMin(ref dp[next, newString.Length], newString);
}
else
{
break;
}
}
}
}
}
var result = Inf;
for (int i = 0; i < graph.NodeCount; i++)
{
ChangeMin(ref result, dp[i, length]);
}
if (result != Inf)
{
io.WriteLine(result);
}
else
{
io.WriteLine(-1);
}
}
/// <summary>
/// <see cref="SCCGraph"/> クラスの新しいインスタンスを、<paramref name="n"/> 頂点 0 辺の有向グラフとして初期化します。
/// </summary>
/// <remarks>
/// <para>制約: 0≤<paramref name="n"/>≤10^8</para>
/// <para>計算量: O(<paramref name="n"/>)</para>
/// </remarks>
public SCCGraph(int n)
{
Debug.Assert(unchecked ((uint)n <= 100_000_000));
_internal = new Internal.SCCGraph(n);
}
