题目描述
Problem Statement
The Kingdom of AtCoder has $N cities called City 1,2,\ldots,N$ and $M roads called Road 1,2,\ldots,M$.
Road i connects Cities A_i and B_i bidirectionally and has a length of C_i.
One can travel between any two cities using some roads.
Under financial difficulties, the kingdom has decided to maintain only N-1 roads so that one can still travel between any two cities using those roads and abandon the rest.
Let d_i be the total length of the roads one must use when going from City 1 to City i using only maintained roads. Print a choice of roads to maintain that minimizes $d_2+d_3+\ldots+d_N$.
Input
Input is given from Standard Input in the following format:
N M
A_1 B_1 C_1
A_2 B_2 C_2
$\vdots$
A_M B_M C_M
Output
Print the indices of roads to maintain, in arbitrary order, with spaces in between.
If multiple solutions exist, you may print any of them.
Constraints
- $2 \leq N \leq 2\times 10^5$
- $N-1 \leq M \leq 2\times 10^5$
- $1 \leq A_i < B_i \leq N$
- $(A_i,B_i)\neq(A_j,B_j)$ if $i\neq j$.
- $1\leq C_i \leq 10^9$
- One can travel between any two cities using some roads.
- All values in input are integers.
Sample Input 1
3 3
1 2 1
2 3 2
1 3 10
Sample Output 1
1 2
Here are the possible choices of roads to maintain and the corresponding values of d_i.
- Maintain Road 1 and 2: d_2=1, d_3=3.
- Maintain Road 1 and 3: d_2=1, d_3=10.
- Maintain Road 2 and 3: d_2=12, d_3=10.
Thus, maintaining Road 1 and 2 minimizes d_2+d_3.
Sample Input 2
4 6
1 2 1
1 3 1
1 4 1
2 3 1
2 4 1
3 4 1
Sample Output 2
3 1 2
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分