bzoj 1003: [ZJOI2006]物流运输trans

题目链接：http://www.lydsy.com/JudgeOnline/problem.php?id=1003

解：一个很神奇的dp，预处理所有连续时间段内的最小花费（w[i][j]表示第i天到第j天的最小花费），然后以f[x]表示到第x天为止的最小花费，用f[j]=min(f[j], f[i]+w[i+1][j]+K)更新即可

/*
 * Problem:  
 * Author:  SHJWUDP
 * Created Time:  2015/6/9 星期二 11:06:58
 * File Name: 233.cpp
 * State: 
 * Memo: 
 */
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>

using namespace std;

const int INF=0x7f7f7f7f;

const int MaxA=100+7;
const int MaxB=20+7;

struct Edge {
    int v, nt;
    int w;
    Edge(){}
    Edge(int v, int nt, int w):v(v), nt(nt), w(w){}
} edges[MaxB*MaxB*2];

int head[MaxB], edgeNum;

struct Data {
    int P, a, b;
} op[MaxA];

int n, m, K, e, d;
int w[MaxA][MaxA];
int f[MaxA];
bool used[MaxA];
void init() {
    memset(head, -1, sizeof(head));
    edgeNum=0;
}
void addEdge(int u, int v, int w) {
    edges[edgeNum]=Edge(v, head[u], w);
    head[u]=edgeNum++;
}
void build(int s, int t) {
    memset(used, 0, sizeof(used));
    for(int i=0; i<d; i++) {
        if(op[i].b<s || op[i].a>t) continue;
        used[op[i].P]=1;
    }
}
namespace Dijkstra {
    struct HeapNode {
        int d, u;
        HeapNode(int d, int u):d(d), u(u) {}
        bool operator<(const HeapNode& rhs) const {
            return d>rhs.d;
        }
    };

    int d[MaxB];
    int done[MaxB];

    void go(int s) {
        priority_queue<HeapNode> Q;
        memset(d, 0x7f, sizeof(d));
        memset(done, 0, sizeof(done));
        
        Q.push(HeapNode(0, s)); d[s]=0;
        while(!Q.empty()) {
            HeapNode x=Q.top(); Q.pop(); 
            if(done[x.u]) continue;
            done[x.u]=1;
            for(int i=head[x.u]; ~i; i=edges[i].nt) {
                Edge& e=edges[i];
                if(used[e.v]) continue;
                if(d[x.u]+e.w<d[e.v]) {
                    d[e.v]=d[x.u]+e.w;
                    Q.push(HeapNode(d[e.v], e.v));
                }
            }
        }
    }
}
int main() {
#ifndef ONLINE_JUDGE
    freopen("in", "r", stdin);
//    freopen("out", "w", stdout);
#endif
    while(~scanf("%d%d%d%d", &n, &m, &K, &e)) {
        init();
        for(int i=0; i<e; i++) {
            int a, b, c;
            scanf("%d%d%d", &a, &b, &c);
            addEdge(a, b, c);
            addEdge(b, a, c);
        }
        scanf("%d", &d);
        for(int i=0; i<d; i++) {
            scanf("%d%d%d", &op[i].P, &op[i].a, &op[i].b);
        }
        for(int i=1; i<=n; i++) {
            for(int j=i; j<=n; j++) {
                build(i, j);
                Dijkstra::go(1);
                w[i][j]=Dijkstra::d[m];
                if(w[i][j]<INF) w[i][j]*=j-i+1;
            }
        }
        for(int j=1; j<=n; j++) {
            f[j]=w[1][j];
            for(int i=1; i<j; i++) {
                if(w[i+1][j]>=INF || f[i]>=INF) continue;
                f[j]=min(f[j], f[i]+w[i+1][j]+K);
            }
        }
        printf("%d
", f[n]);
    }
    return 0;
}