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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