bzoj 1520 [POI2006]Szk-Schools 费用流
[POI2006]Szk-Schools
Time Limit: 5 Sec Memory Limit: 64 MBSubmit: 743 Solved: 381
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Description
![](https://www.lydsy.com/JudgeOnline/images/1520_1.jpg)
Input
![](https://www.lydsy.com/JudgeOnline/images/1520_2.jpg)
Output
如果有可行解, 输出最小代价,否则输出NIE.
Sample Input
5
1 1 2 3
1 1 5 1
3 2 5 5
4 1 5 10
3 3 3 1
1 1 2 3
1 1 5 1
3 2 5 5
4 1 5 10
3 3 3 1
Sample Output
9
HINT
考虑数据范围应该就是比较裸的费用流吧
1 #include<iostream> 2 #include<cstdio> 3 #include<cstdlib> 4 #include<algorithm> 5 #include<cmath> 6 #include<cstring> 7 #include<set> 8 #include<queue> 9 #include<map> 10 #define pa pair<int,int> 11 #define mod 1000000007 12 #define inf 1000000000 13 #define ll long long 14 using namespace std; 15 int read() 16 { 17 int x=0,f=1;char ch=getchar(); 18 while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} 19 while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} 20 return x*f; 21 } 22 int n,cnt=1,T,tot,ans; 23 int last[405],h[405],q[405],d[405]; 24 bool inq[405]; 25 struct data{int to,next,c,v;}e[100005]; 26 void ins(int u,int v,int w,int c) 27 { 28 e[++cnt].to=v;e[cnt].next=last[u];last[u]=cnt;e[cnt].v=w;e[cnt].c=c; 29 } 30 void insert(int u,int v,int w,int c) 31 { 32 ins(u,v,w,c); 33 ins(v,u,0,-c); 34 } 35 bool spfa() 36 { 37 memset(inq,0,sizeof(inq)); 38 int head=0,tail=1; 39 for(int i=0;i<=T;i++)d[i]=inf; 40 q[0]=T;d[T]=0;inq[T]=1; 41 while(head!=tail) 42 { 43 int now=q[head];head++;if(head==405)head=0; 44 for(int i=last[now];i;i=e[i].next) 45 if(e[i^1].v&&d[now]-e[i].c<d[e[i].to]) 46 { 47 d[e[i].to]=d[now]-e[i].c; 48 if(!inq[e[i].to]) 49 { 50 inq[e[i].to]=1; 51 q[tail]=e[i].to; 52 tail++;if(tail==405)tail=0; 53 } 54 } 55 inq[now]=0; 56 } 57 return d[0]!=inf; 58 } 59 int dfs(int x,int f) 60 { 61 inq[x]=1; 62 if(x==T)return f; 63 int used=0,w; 64 for(int i=last[x];i;i=e[i].next) 65 if(!inq[e[i].to]&&e[i].v&&d[x]-e[i].c==d[e[i].to]) 66 { 67 w=f-used; 68 w=dfs(e[i].to,min(e[i].v,w)); 69 ans+=w*e[i].c; 70 e[i].v-=w;e[i^1].v+=w; 71 used+=w;if(used==f)return f; 72 } 73 return used; 74 } 75 void zkw() 76 { 77 while(spfa()) 78 { 79 inq[T]=1; 80 while(inq[T]) 81 { 82 memset(inq,0,sizeof(inq)); 83 tot+=dfs(0,inf); 84 } 85 } 86 } 87 int main() 88 { 89 n=read();T=2*n+1; 90 for(int i=1;i<=n;i++)insert(0,i,1,0); 91 for(int i=1;i<=n;i++)insert(i+n,T,1,0); 92 for(int i=1;i<=n;i++) 93 { 94 int m=read(),a=read(),b=read(),k=read(); 95 for(int j=a;j<=b;j++) 96 insert(i,n+j,1,abs((j-m)*k)); 97 } 98 zkw(); 99 if(tot!=n)puts("NIE"); 100 else printf("%d\n",ans); 101 return 0; 102 }