No.1607 Kth Maximum Card
タグ : / 解いたユーザー数 95
作問者 :
SPD_9X2
/ テスター :
👑
tute7627
penguinman
Problem Statement
You are given a simple undirected graph with $N$ vertices and $M$ edges. The graph as a whole is guaranteed to be connected.
Edge $i$ ($1 \le i \le M$) connects vertices $u_i$ and $v_i$ and has a parameter $c_i$.
Seneko has a bag, which initially contains $K$ cards with $0$ written on them.
Seneko starts at vertex $1$ and travels on the graph.
When Seneko traverses edge $i$, she puts $1$ card with $c_i$ written on it into the bag. (If she traverses the same edge multiple times, she puts in $1$ card each time.)
Some time after starting the journey, Seneko was at vertex $N$. At this point, find the minimum possible value of the number written on the card that comes $K$-th when the cards in the bag are arranged in descending order.
Note that Seneko moves only between $2$ vertices connected by an edge, and she may use the same edge $2$ or more times.
Input
$N\ M\ K$ $u_1\ v_1\ c_1$ $u_2\ v_2\ c_2$ $\vdots$ $u_M\ v_M\ c_M$
- All inputs are integers.
- The given graph is a connected simple undirected graph.
- $2 \le N \le 2 \times 10^5$
- $N-1 \le M \le \mathrm{min}\left(2 \times 10^5, \frac{N (N - 1)} {2}\right)$
- $1 \le K \le 2 \times 10^5$
- $1 \le u_i < v_i \le N$
- If $i \neq j $, then $(u_i,v_i) \neq (u_j,v_j)$
- $1 \le c_i \le 2 \times 10^5$
Output
Output the answer on one line. End the output with a newline.
Sample
Sample 1
Input
2 1 1 1 2 100
Output
100
Sample 2
Input
2 1 2 1 2 100
Output
0
The card with 0 that was in the bag from the beginning is the 2nd largest card.
Sample 3
Input
4 4 2 1 2 50 2 4 50 1 3 100 3 4 1
Output
1
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