HDU-2544 最短路【最短路】

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2544

最近复习了最短路径的算法，就写了4个版本的测试。正好是模板题，就果断A之。。。

Dijkstar版本：

#include
#include
#include
#include
#include
#include
#include
using namespace std;

#define N 110
#define MAX 999999
#define CLR(arr, what) memset(arr, what, sizeof(arr))

int nodenum, edgenum;
int map[N][N], dis[N];
bool visit[N];

int Dijkstra(int src, int des)
{
    int temp, k;
    CLR(visit, false);
    for(int i = 1; i <= nodenum; ++i)
        dis[i] = (i == src ? 0 : map[src][i]);
    visit[src] = true;
    dis[src] = 0;
    for(int i = 1; i<= nodenum; ++i)
    {
        temp = MAX;
        for(int j = 1; j <= nodenum; ++j)
            if(!visit[j] && temp > dis[j])
                temp = dis[k = j];
        if(temp == MAX)
            break;
        visit[k] = true;
        for(int j = 1; j <= nodenum; ++j)
            if(!visit[j] && dis[j] > dis[k] + map[k][j])
                dis[j] = dis[k] + map[k][j];
    }
    return dis[des];
}

int main()
{
    int start, end, cost;
    int answer;
    while(~scanf("%d%d", &nodenum, &edgenum) && (nodenum + edgenum))
    {
        for(int i = 1; i <= nodenum; ++i)
            for(int j = 1; j <= nodenum; ++j)
            map[i][j] = MAX;
        for(int i = 1; i <= edgenum; ++i)
        {
            scanf("%d%d%d", &start, &end, &cost);
            if(cost < map[start][end])
                map[start][end] = map[end][start] = cost;
        }
        answer = Dijkstra(1, nodenum);
        printf("%d\n", answer);
    }
    return 0;
}

Bellman_Ford版本：

#include
#include
#include
#include
#include
#include
#include
using namespace std;

#define N 110
#define MAX 999999
#define CLR(arr, what) memset(arr, what, sizeof(arr))

int nodenum, edgenum;
int map[N][N], dis[N];
bool visit[N];

struct Edge
{
    int u, v;
    int cost;
}e[N * N / 2];

int Bellman_ford(int src, int des)
{
    for(int i = 1; i <= nodenum; ++i)
        dis[i] = MAX;
    dis[src] = 0;
    for(int i = 0; i < nodenum - 1; ++i) //n-1遍
        for(int j = 0; j < edgenum * 2; ++j) //each edge
            if(dis[e[j].v] > dis[e[j].u] + e[j].cost)
                dis[e[j].v] = dis[e[j].u] + e[j].cost;
    return dis[des];
}

int main()
{
    int start, end, cost;
    int answer;
    while(~scanf("%d%d", &nodenum, &edgenum) && (nodenum + edgenum))
    {
        for(int i = 0; i < edgenum; ++i)
        {
            scanf("%d%d%d", &start, &end, &cost); //双向边
            e[i * 2].u = start, e[i * 2].v = end, e[i * 2].cost = cost;
            e[i * 2 + 1].u = end, e[i * 2 + 1].v = start, e[i * 2 + 1].cost = cost;
        }
        answer = Bellman_ford(1, nodenum);
        printf("%d\n", answer);
    }
    return 0;
}

Floyd版本：

#include
#include
#include
#include
#include
#include
#include
using namespace std;

#define N 110
#define MAX INT_MAX >> 1
#define CLR(arr, what) memset(arr, what, sizeof(arr))

int nodenum, edgenum;
int map[N][N], dis[N];
bool visit[N];

int Floyd(int src, int des) //多源多汇最短路
{
    for(int k = 1; k <= nodenum; ++k)
        for(int i = 1; i <= nodenum; ++i)
            for(int j = 1; j <= nodenum; ++j)
                map[i][j] = min(map[i][j], map[i][k] + map[k][j]);
    return map[src][des];
}

int main()
{
    int start, end, cost;
    int answer;
    while(~scanf("%d%d", &nodenum, &edgenum) && (nodenum + edgenum))
    {
        for(int i = 1; i <= nodenum; ++i)
            for(int j = 1; j <= nodenum; ++j)
                map[i][j] = MAX;
        for(int i = 0; i < edgenum; ++i)
        {
            scanf("%d%d%d", &start, &end, &cost);
            if(cost < map[start][end])
                map[start][end] = map[end][start] = cost;
        }
        answer = Floyd(1, nodenum);
        printf("%d\n", answer);
    }
    return 0;
}

SPFA版本：

#include
#include
#include
#include
#include
#include
#include
using namespace std;

#define N 110
#define MAX INT_MAX >> 1
#define CLR(arr, what) memset(arr, what, sizeof(arr))

int nodenum, edgenum;
int map[N][N], dis[N];
bool visit[N];

int SPFA(int src, int des)
{
    queue q;
    CLR(visit, false);
    for(int i = 1;i <= nodenum; ++i)
        dis[i] = MAX;
    dis[src] = 0;
    visit[src] = true;

    q.push(src);
    while(!q.empty())
    {
        int cur = q.front();
        q.pop();
        visit[cur] = false; //出队标记为false
        for(int i = 1; i <= nodenum; ++i)
        {
            if(dis[i] > dis[cur] + map[cur][i]) //没有2个集合，和Dijkstra有本质区别
            {
                dis[i] = dis[cur] + map[cur][i]; //能松弛就松弛
                if(!visit[i]) //不在队列中则加入，然后更新所有以前经过此点的最短路径
                {
                    q.push(i);
                    visit[i] = true;
                }
            }
        }
    }
    return dis[des];
}

int main()
{
    int start, end, cost;
    int answer;
    while(~scanf("%d%d", &nodenum, &edgenum) && (nodenum + edgenum))
    {
        for(int i = 1; i <= nodenum; ++i)
            for(int j = 1; j <= nodenum; ++j)
                map[i][j] = MAX;
        for(int i = 0; i < edgenum; ++i)
        {
            scanf("%d%d%d", &start, &end, &cost);
            if(cost < map[start][end])
                map[start][end] = map[end][start] = cost;
        }
        answer = SPFA(1, nodenum);
        printf("%d\n", answer);
    }
    return 0;
}