fr.cpp

 
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
 
using namespace std;
 
int traverse(int node, bool *visited, int **mat, int n) {
	visited[node] = true;
	int total = 0;
	for (int i = 0; i < n; i++) {
		if (!visited[i] && mat[node][i]) {
			int sub = traverse(i, visited, mat, n);
			total += sub && sub < mat[node][i] ? sub : mat[node][i];
		}
	}
	return total;
}
 
int main() {
	int nn, nc;
	scanf("%d %d", &nn, &nc);
	bool quit = false;
	while (!quit) {
		int n = nn;
		int c = nc;
 
		// prepare
		int **mat = new int *[n];
		int *matInner = new int[n*n];
		memset(matInner, 0, n*n*sizeof(int));
		for (int i = 0; i < n; i++)
			mat[i] = matInner+i*n;
 
		// read edges
		int u, v, w;
		while (scanf("%d %d", &u, &v) == 2) {
			if (getchar() == '\n') {
				nn = u;
				nc = v;
				goto CMPT;
			}
			scanf("%d", &w);
			// use edge u, v, w
			u--, v--;
			mat[u][v] = mat[v][u] = w;
		}
		quit = true;
		CMPT:
		// compute here
		c--;
		bool *visited = new bool[n];
		memset(visited, 0, n*sizeof(bool));
		int result = traverse(c, visited, mat, n);
		printf("%d\n", result);
		// dealloc
		delete [] mat;
		delete [] matInner;
	}
	return 0;
}