#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
const int inf = 1<<30;
int n;
int map[205][205];
int a[205], cnt;
int vis[205], cast[205];
void Dijkstra(int s, int e) {
int i, j, min, pos;
memset(vis, 0, sizeof(vis));
for(i = 0; i < n; i++)
cast[i] = map[s][i];
cast[s] = 0;
vis[s] = 1;
for(i = 1; i < n; i++) {
min = inf;
for(j = 0; j < n; j++) {
if(cast[j]<min && !vis[j]) {
pos = j;
min = cast[j];
}
}
if(min == inf)
break;
vis[pos] = 1;
for(j = 0; j < n; j++) {
if(cast[pos] + map[pos][j] < cast[j] && !vis[j])
cast[j] = cast[pos] + map[pos][j];
}
}
}
int main() {
int i, j, s, e, x, y;
while(~scanf("%d", &n), n) {
scanf("%d%d", &s, &e);
s--,e--;
for(i = 0; i < n; i++)
for(j = 0; j < n; j++)
map[i][j] = inf;
for(i = 0; i < n; i++) {
scanf("%d",&a[i]);
if(i+a[i] < n)
map[i][i+a[i]] = 1;
if(i-a[i]>=0)
map[i][i-a[i]] = 1;
}
Dijkstra(s,e);
printf("%d\n",cast[e] == inf ? -1: cast[e]);
}
return 0;
}
HDU 1548 A strange lift(Dijkstra)
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转载自blog.csdn.net/ccshijtgc/article/details/83268849
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