Problem p00929 - Generation 3

Orig Description

Problem F:
There is No Alternative
  ICPC (Isles of Coral Park City) consist of several beautiful islands.
  The citizens requested construction of bridges between islands to resolve inconveniences of using boats between islands, and they demand that all the islands should be reachable from any other islands via one or more bridges.
  The city mayor selected a number of pairs of islands, and ordered a building company to estimate the costs to build bridges between the pairs. With this estimate, the mayor has to decide the set of bridges to build, minimizing the total construction cost.
  However, it is difficult for him to select the most cost-efficient set of bridges among those connecting all the islands. For example, three sets of bridges connect all the islands for the Sample Input 1. The bridges in each set are expressed by bold edges in Figure F.1.
Figure F.1. Three sets of bridges connecting all the islands for Sample Input 1
  As the first step, he decided to build only those bridges which are contained in all the sets of bridges to connect all the islands and minimize the cost. We refer to such bridges as no alternative bridges. In Figure F.2, no alternative bridges are drawn as thick edges for the Sample Input 1, 2 and 3.
Figure F.2. No alternative bridges for Sample Input 1, 2 and 3
Write a program that advises the mayor which bridges are no alternative bridges for the given input.
Input
The input consists of a single test case.
  
$N$ $M$
$S_1$ $D_1$ $C_1$
.
.
.
$S_M$ $D_M$ $C_M$
The first line contains two positive integers $N$ and $M$. $N$ represents the number of islands and each island is identified by an integer 1 through $N$. $M$ represents the number of the pairs of islands between which a bridge may be built.
Each line of the next $M$ lines contains three integers $S_i$, $D_i$ and $C_i$ ($1 \leq i \leq M$) which represent that it will cost $C_i$ to build the bridge between islands $S_i$ and $D_i$. You may assume $3 \leq N \leq 500$, $N − 1 \leq M \leq min(50000, N(N − 1)/2)$, $1 \leq S_i < D_i \leq N$, and $1 \leq C_i \leq 10000$. No two bridges connect the same pair of two islands, that is, if $i \ne j$ and $S_i = S_j$, then $D_i \ne D_j$ . If all the candidate bridges are built, all the islands are reachable from any other islands via one or more bridges.
Output
Output two integers, which mean the number of no alternative bridges and the sum of their construction cost, separated by a space.
Sample Input 1
4 4
1 2 3
1 3 3
2 3 3
2 4 3
Sample Output 1
1 3
Sample Input 2
4 4
1 2 3
1 3 5
2 3 3
2 4 3
Sample Output 2
3 9
Sample Input 3
4 4
1 2 3
1 3 1
2 3 3
2 4 3
Sample Output 3
2 4
Sample Input 4
3 3
1 2 1
2 3 1
1 3 1
Sample Output 4
0 0

Extracted Specification

An integer \( N \) (3 ≤ \( N \) ≤ 500), representing some quantity.
An integer \( M \) (\( N \)-1 ≤ \( M \) ≤ min(50000, \( N(N-1)/2 \)), representing another quantity.
A list of \( M \) tuples, each containing three integers \( S \), \( D \), and \( C \) (1 ≤ \( S \) < \( D \) ≤ \( N \); 1 ≤ \( C \) ≤ 10000).

### Example Input:

```
4 4
1 2 3
1 3 3
2 3 3
2 4 3
```

### Function Signature:
Write a function f(N, M, bridges) that takes in the input.
```python
def f(N: int, M: int, bridges: List[Tuple[int, int, int]]):
    '''
    N: an integer
    M: an integer
    bridges: a list of tuples, each containing three integers
    '''
```

Test Case Generator

Sure, I can help with that! Here's a test case generator for the given problem statement "There is No Alternative":

```python
import random

def tcgen():
    # Number of islands
    N = random.randint(3, 500)
    
    # Number of possible bridges
    M = random.randint(N - 1, min(50000, N * (N - 1) // 2))
    
    bridge_set = set()
    
    # Generate M bridges
    bridges = []
    for _ in range(M):
        while True:
            S = random.randint(1, N - 1)
            D = random.randint(S + 1, N)
            if (S, D) not in bridge_set:
                bridge_set.add((S, D))
                break
        C = random.randint(1, 10000)
        bridges.append((S, D, C))
    
    return N, M, bridges

# Printing a test case example
N, M, bridges = tcgen()
print(N, M)
for bridge in bridges:
    print(bridge[0], bridge[1], bridge[2])
```

This test case generator produces random test cases for the given problem. Here's a breakdown of what it does:

1. **Number of Islands (`N`)**: Picks a random number of islands between 3 and 500.
2. **Number of Possible Bridges (`M`)**: Picks a random number of bridges between `N - 1` and the minimum of 50000 and the maximum possible number of unique bridges for `N` islands.
3. **Bridge Generation**: Ensures that each pair of islands `(S, D)` is unique and generates a random cost `C` for each bridge.
4. **Output**: Prints the number of islands, the number of bridges, and the details of each bridge.

You can run this script to generate different test cases as needed.

Extract Arguments

def extract_arguments(fh):
    N, M = map(int, fh.readline().strip().split())
    bridges = []
    for _ in range(M):
        S, D, C = map(int, fh.readline().strip().split())
        bridges.append((S, D, C))
    return N, M, bridges

# if __name__ == "__main__":
#     input_path = sys.argv[1]
#     with open(input_path, 'r') as fh:
#         N, M, bridges = extract_arguments(fh)
#         f(N, M, bridges)