fr.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
 
int conn[2000][2000];
int pipes[2000];
int nodes;
 
int count(int node, int from) {
	int i, inputc= 1000000000, childc = 0;
	//printf("count node %d from %d\n", node, from);
	if (pipes[node]==1 && from != -1) {
		//printf("leaf %d\n", node);
		return conn[node][from];
	}
	for (i=1; i<nodes+1; i++) {
		if (i==from) {
			inputc = conn[node][i];
		} else {
			//childc += conn[node][i];
			if (conn[node][i] > 0) childc += count(i, node);
		}
	}
	//printf("node %d from %d input %d child %d\n", node, from, inputc, childc);
	if (childc == 0) return inputc;
	return childc > inputc ? inputc : childc;
}
 
int main(int argc, char **argv)
{
	int rv, root, i, n1, n2, w;
	while (1) {
		rv = scanf("%d%d", &nodes, &root);
		if (rv != 2) break;
		memset(conn, 0, sizeof(conn));
		memset(pipes, 0, sizeof(pipes));
		for (i=0; i<nodes-1; i++) {
			scanf("%d%d%d", &n1, &n2, &w);
			conn[n1][n2] = w;
			conn[n2][n1] = w;
			pipes[n1]++;
			pipes[n2]++;
		}
		printf("%d\n", count(root, -1));
	}
	return 0;
}
 

fr.c