sicily 1031. Campus 单源最短路

       这题做得无比纠结~~~WA了无数次，一开始以为算法错了， 调了半天发现不了问题， 最后还是看别人解题报告才过，

原来当输入的S和T不在列表且S=T时，是要输出0的，这个要注意~~

      主要是用一个map把字符串映射到数字

#include <iostream>

#include <string>

#include <map>

#include <memory.h>

#define INF 1000000

#define MAX 210

using namespace std;



int cost[MAX][MAX];

int my_distance[MAX];

bool isvisit[MAX];



int n;

int edge_count;



void shortest_path(int);

int main()

{

	int cases;

	int  start, goal;

	string a, b;

	int distance;



	int count;

	map<string, int> name;

	map<string, int>::iterator iter1, iter2;



	cin >> cases;

	while (cases--)

	{



		cin >> n;



		for (int i = 0; i < MAX; i++)

			for (int j = 0; j < MAX; j++)

				if (i != j) cost[i][j] = INF;

				else cost[i][j] = 0;



		count = 0;

		for (int i = 0; i < n; i++)

		{

			cin >> a >> b >> distance;

			iter1 = name.find(a);

			iter2 = name.find(b);

			if (iter1 != name.end() && iter2 != name.end())

			{

				cost[iter1->second][iter2->second] = distance;

				cost[iter2->second][iter1->second] = distance;

			}

			else if (iter1 == name.end() && iter2 == name.end())

			{

				if (a != b)

				{

					cost[count][count+1] = distance;

					cost[count+1][count] = distance;

					name.insert(pair<string, int>(a, count++));

					name.insert(pair<string, int>(b, count++));

				}

				else

				{

					cost[count][count] = distance;

					name.insert(pair<string, int>(a, count++));

				}



			}

			else if (iter1 == name.end() && iter2 != name.end())

			{

				cost[count][iter2->second] = distance;

				cost[iter2->second][count] = distance;

				name.insert(pair<string, int>(a, count++));

			}

			else 

			{

				cost[count][iter1->second] = distance;

				cost[iter1->second][count] = distance;

				name.insert(pair<string, int>(b, count++));

			}

		}



		edge_count = count;

		cin >> a >> b;

		iter1 = name.find(a);

		iter2 = name.find(b);



		if (iter1 != name.end() && iter2 != name.end())

		{

			start =(name.find(a))->second;

			goal = (name.find(b))->second;



			shortest_path(start);



			if (my_distance[goal] < INF)

				cout << my_distance[goal] << endl;

			else

				cout << "-1" << endl;



		}

		else if (a == b)

			cout << "0" << endl;

		else

			cout << "-1" << endl;



		name.clear();

	}

	return 0;

}



void shortest_path(int start)

{

	memset(isvisit, false, sizeof(isvisit));



	for (int i = 0; i < edge_count; i++)

		my_distance[i] = cost[start][i];



	isvisit[start] = true;

	int _min = INF, min_point;

	int next;



	for (int i = 0; i < edge_count-1; i++)

	{

		_min = INF;

		for (int j = 0; j < edge_count; j++)

			if (!isvisit[j] && _min > my_distance[j])

			{

				_min = my_distance[j];

				min_point = j;

			}



		isvisit[min_point] = true;



		for (int j = 0; j < edge_count; j++)

			if (!isvisit[j] && my_distance[j] > cost[min_point][j] + my_distance[min_point])

				my_distance[j] =  cost[min_point][j] + my_distance[min_point];



	}

}