[BZOJ1001][BeiJing2006]狼抓兔子

#include <queue>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
char buf[10000000], *ptr = buf - 1;
inline int readint(){
    int n = 0;
    char ch = *++ptr;
    while(ch < ‘0‘ || ch > ‘9‘) ch = *++ptr;
    while(ch <= ‘9‘ && ch >= ‘0‘){
        n = (n << 1) + (n << 3) + ch - ‘0‘;
        ch = *++ptr;
    }
    return n;
}
const int INF = 2147483647;
struct Edge{
    int to, val, next;
    Edge(){}
    Edge(int _t, int _v, int _n): to(_t), val(_v), next(_n){}
}e[6000000];
int fir[2000000] = {0}, cnt = 0;
inline void ins(int u, int v, int w){
    e[++cnt] = Edge(v, w, fir[u]); fir[u] = cnt;
    e[++cnt] = Edge(u, w, fir[v]); fir[v] = cnt; 
}
int n, m, nm;
struct Node{
    int dis, idx;
    Node(){}
    Node(int _d, int _i): dis(_d), idx(_i){}
}t;
class cmp{
    public:
        bool operator () (const Node &a, const Node &b){
            return a.dis > b.dis;
        }
};
priority_queue<Node, vector<Node>, cmp> pq;
int S, T;
bool state[2000000];
int dis[2000000];
int dijkstra(){
    for(int i = T; i; i--){
        dis[i] = INF;
        state[i] = false;
    }
    dis[S] = 0;
    pq.push(Node(0, S));
    int u, v;
    while(!pq.empty()){
        t = pq.top(); pq.pop();
        if(state[t.idx]) continue;
        u = t.idx;
        state[u] = true;
        for(int i = fir[u]; i; i = e[i].next){
            v = e[i].to;
            if(dis[v] > dis[u] + e[i].val){
                dis[v] = dis[u] + e[i].val;
                pq.push(Node(dis[v], v));
            }
        }
    }
}
int main(){
    fread(buf, sizeof(char), sizeof(buf), stdin);
    n = readint();
    m = readint();
    if(n != 1 && m != 1){
        nm = (n - 1) * (m - 1);
        S = 2 * nm + 1;
        T = S + 1;
        int u, v;
        for(int i = 1; i <= n; i++)
            for(int j = 1; j < m; j++){
                u = i == 1 ? T : (i - 2) * (m - 1) + j + nm;
                v = i == n ? S : (i - 1) * (m - 1) + j;
                ins(u, v, readint());
            }
        for(int i = 1; i < n; i++)
            for(int j = 1; j <= m; j++){
                u = j == 1 ? S : (i - 1) * (m - 1) + j - 1;
                v = j == m ? T : (i - 1) * (m - 1) + j + nm;
                ins(u, v, readint());
            }
        for(int i = 1; i < n; i++)
            for(int j = 1; j < m; j++){
                u = (i - 1) * (m - 1) + j;
                v = u + nm;
                ins(u, v, readint());
            }
        dijkstra();
        printf("%d\n", dis[T]);
    }
    else{
        int ans = INF;
        if(m == 1) swap(n, m);
        for(int i = 1; i < m; i++)
            ans = min(ans, readint());
        printf("%d\n", ans);
    }
    return 0;
}