BZOJ 1003 物流运输trans dijstra+dp
题目链接:
http://www.lydsy.com/JudgeOnline/problem.php?id=1003
题意:
题解:
首先我们必须机智的知道f[i]=min(f[i],f[j]+cost(j+1,i)+k)这个dp方程
cost(i,j)表示从第i天到第j天的最小花费
dijstra跑一发
代码:
1 #include <bits/stdc++.h> 2 using namespace std; 3 typedef long long ll; 4 #define MS(a) memset(a,0,sizeof(a)) 5 #define MP make_pair 6 #define PB push_back 7 const int INF = 9999999; 8 const ll INFLL = 0x3f3f3f3f3f3f3f3fLL; 9 inline ll read(){ 10 ll x=0,f=1;char ch=getchar(); 11 while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} 12 while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} 13 return x*f; 14 } 15 ////////////////////////////////////////////////////////////////////////// 16 const int maxn = 1e2+10; 17 18 int n,m,k,e; 19 int flag[maxn][maxn],f[maxn],d[maxn],dp[maxn]; 20 vector<pair<int,int> > G[maxn]; 21 22 int cost(int s,int e){ 23 MS(f); 24 for(int i=1;i<=m;i++) 25 d[i]=INF; 26 27 for(int i=1; i<=m; i++){ 28 for(int j=s; j<=e; j++) 29 if(flag[i][j]) 30 f[i] = 1; 31 } 32 33 queue<int> q; 34 d[1] = 0; 35 q.push(1); 36 while(!q.empty()){ 37 int u = q.front(); q.pop(); 38 for(int i=0; i<(int)G[u].size(); i++){ 39 pair<int,int> p = G[u][i]; 40 int v = p.first, w = p.second; 41 if(f[v]) continue; 42 if(d[v] > d[u]+w){ 43 d[v] = d[u]+w; 44 q.push(v); 45 } 46 } 47 } 48 // cout << d[m] << " pp\n"; 49 int ans = d[m]*(e-s+1); 50 return ans; 51 } 52 53 int main(){ 54 scanf("%d%d%d%d",&n,&m,&k,&e); 55 for(int i=0; i<e; i++){ 56 int u,v,w; scanf("%d%d%d",&u,&v,&w); 57 G[u].push_back(MP(v,w)); 58 G[v].push_back(MP(u,w)); 59 } 60 61 int d = read(); 62 for(int i=0; i<d; i++){ 63 int u,ii,jj; 64 scanf("%d%d%d",&u,&ii,&jj); 65 for(int j=ii; j<=jj; j++) 66 flag[u][j] = 1; 67 } 68 // cout << "hh\n"; 69 for(int i=1; i<=n; i++){ 70 dp[i] = cost(1,i); 71 // cout << dp[i] << " kk\n"; 72 for(int j=1; j<i; j++) 73 dp[i] = min(dp[i],dp[j]+cost(j+1,i)+k); 74 } 75 76 cout << dp[n] << endl; 77 78 return 0; 79 }
