TYVJ2032 「Poetize9」升降梯上

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <vector>
  4 #include <cstdlib>
  5 #include <cstring>
  6 #include <queue>
  7 #define max(a, b) ((a) > (b) ? (a) : (b))
  8 #define min(a, b) ((a) < (b) ? (a) : (b))
  9 #define abs(a) ((a) < 0 ? (-1 * (a)) : (a)) 
 10 
 11 const int INF = 0x3f3f3f3f;
 12 const int MAXN = 1000 + 10;
 13 const int MAXM = 20 + 5;
 14 
 15 inline void read(int &x)
 16 {
 17     x = 0;char ch = getchar(), c = ch;
 18     while(ch < ‘0‘ || ch > ‘9‘) c = ch, ch = getchar();
 19     while(ch <= ‘9‘ && ch >= ‘0‘) x = x * 10 + ch - ‘0‘, ch = getchar();
 20     if(c == ‘-‘)x = -x; 
 21 }
 22 
 23 int n,m;
 24 
 25 inline int number(int a, int b)
 26 {
 27     return (a - 1) * m + b - 1;
 28 }
 29 
 30 struct Edge
 31 {
 32     int u,v,w,next;
 33     Edge(int _u, int _v, int _w, int _next){u = _u;v = _v;w = _w;next = _next;}
 34     Edge(){}
 35 }edge[MAXN * MAXM * MAXM * 4];
 36 int head[MAXN * MAXM * 2], cnt, c[MAXN];
 37 
 38 inline void insert(int a, int b, int c)
 39 {
 40     edge[++cnt] = Edge(a,b,c,head[a]);
 41     head[a] = cnt;
 42 }
 43 
 44 struct Node
 45 {
 46     int node,w;
 47     Node(int a, int b){node = a;w = b;}
 48     Node(){}
 49 };
 50 
 51 struct cmp
 52 {
 53     bool operator()(Node a, Node b)
 54     {
 55         return a.w > b.w;
 56     }
 57 };
 58 
 59 std::priority_queue<Node, std::vector<Node>, cmp> q;
 60 int s, d[MAXN * MAXM * 2], b[MAXN * MAXM * 2];
 61 
 62 void dijstra()
 63 {
 64     memset(d, 0x3f, sizeof(d));
 65     d[s] = 0;
 66     q.push(Node(s, 0));
 67     Node tmp;
 68     int u,v;
 69     while(q.size())
 70     {
 71         tmp = q.top(), q.pop();
 72         if(b[tmp.node])continue;
 73         u = tmp.node;
 74         b[u] = 1;
 75         for(register int pos = head[u];pos;pos = edge[pos].next)
 76         {
 77             v = edge[pos].v;
 78             if(b[v])continue;
 79             if(d[v] > d[u] + edge[pos].w)
 80             {
 81                 d[v] = d[u] + edge[pos].w;
 82                 q.push(Node(v, d[v])); 
 83             } 
 84         }
 85     }
 86 }
 87 
 88 int main()
 89 {
 90     read(n), read(m);
 91     for(register int i = 1;i <= m;++ i)
 92     {
 93         read(c[i]);
 94         if(c[i] == 0)s = number(1, i);
 95     }
 96     for(register int i = 1;i < n;++ i)
 97     {
 98         for(int j = 1;j <= m;++ j)
 99         {
100             if(i + c[j] > 0 && i + c[j] <= n && c[j] != 0)
101                 insert(number(i,j), number(i + c[j], j), abs(c[j]) * 2);
102             for(int k = 1;k <= m;++ k)
103                 if(k != j)
104                     insert(number(i, j), number(i, k), abs(j - k));
105         }
106     }
107     dijstra();
108     int ans = INF;
109     for(register int i = 1;i <= m;++ i)
110         ans = min(ans, d[number(n, i)]);
111     if(ans == INF)ans = -1;
112     printf("%d", ans);
113     return 0;
114 }