P1135奇怪的电梯

P1135奇怪的电梯

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int n,a,b;
long long dis[210][210];

int main(){
    //freopen("in","r",stdin);
    cin >> n >> a >> b;
    if(a == b){
        cout << 0 << endl;
        return 0;
    }
    for(int i = 0; i <= n; i++)
        for(int j = 0; j <= n; j++)
            dis[i][j] = 1e17;
        for(int i = 1; i <= n; i++){
            int x;
            cin >> x;
            if(i > x)
                dis[i][i - x] = 1;
            if( i + x <= n)
                dis[i][i + x] = 1;
        }
        for(int k = 1; k <= n; k++)
            for(int i = 1; i <= n; i++)
                for(int j = 1; j <= n; j++)
                    if(dis[i][j] > dis[i][k] + dis[k][j])
                        dis[i][j] = dis[i][k] + dis[k][j];
        if(dis[a][b] == 1e17)
            cout << "-1";
        else cout << dis[a][b];
    return 0;
}

for(int i = 0; i < G.vexnum; i++)
    for(int j = 0; j < G.vexnum; j++){
        D[i][j] = G.arcs[i][j];
        //如果i j之间又弧;将j的前驱置为i;
        if(D[i][j] < MaxInt && i != j)
            Path[i][j] = i;
        //否则-1；
        else Path[i][j] = -1;

    }
for(int k = 0; k < G.vexnum; k++)
    for(int i = 0; i < G.vexnum; i++)
        for(int j = 0; j < G.vexnum; j++)
            //从i经k到j的一条路径更短
            if(D[i][k] + D[k][j] < D[i][j]){

                D[i][j] = D[i][k] + D[k][j];
                //将j前驱改为k
                Path[i][j] = Path[k][j];
            }