HDU_1548 A strange lift(最短路 Dijkstra解法)

把与某个楼成相连的上下楼层为边建立一个图，边的权值为1.

如：3 3 1 2 5

可建成图：

map[1][4] = 1;

map[2][5] = 1;

map[3][2] = 1;

map[3][4] = 1;

map[4][2] = 1;

然后用最短路经的解法Floyd, Bellman_Ford, SPFA, Dijkstra...

这里用的是Dijkstra解法

My Code:

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;

const int inf = 10000000;
const int N = 207;

int map[N][N];
int dis[N], vis[N];
int n;
void Dijkstra(int v)
{
    int i, j;
    memset(vis, 0, sizeof(vis));        //这里是个陷阱，记得要memset(vis, 0, sizeof(vis));，在这里查bug查了好一会！
    for(i = 1; i <= n; i++)
    {
        dis[i] = map[v][i];
        //printf("%d ", map[v][i]);
    }
    dis[v] = 0;
    vis[v] = 1;
    for(i = 2; i <= n; i++)
    {
        int flag = v, min = inf;
        for(j = 1; j <= n; j++)
            if(!vis[j] && dis[j] < min)
            {
                flag = j;
                min = dis[j];
            }
        vis[flag] = 1;
        for(j = 1; j <= n; j++)
        {
            if(!vis[j] && map[flag][j] < inf)
            {
                int newdis = dis[flag] + map[flag][j];
                if(newdis < dis[j])
                    dis[j] = newdis;
            }
        }
    }
}

int main()
{
    //freopen("data.in", "r", stdin);
    int v, u, x;
    while(scanf("%d", &n), n)
    {
        scanf("%d%d", &v, &u);
        int i, j;
        for(i = 1; i <= n; i++)
            for(j = 1; j <= n; j++)
                map[i][j] = inf;
        for(i = 1; i <= n; i++)
        {
            scanf("%d", &x);
            if(i+x <= n)
                map[i][i+x] = 1;
            if(i-x >= 1)
                map[i][i-x] = 1;
        }
        /*for(i = 1; i <= n; i++)
        {
            for(j = 1; j <= n; j++)
                printf("%10d", map[i][j]);
            printf("\n");
        }*/
        Dijkstra(v);
        /*for(i = 1; i <= n; i++)
            printf("%d ", dis[i]);
        printf("\n");*/
        if(dis[u] < inf)
            printf("%d\n", dis[u]);
        else
            printf("-1\n");
    }
    return 0;
}

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