网络流24题-1

网络流24题-1

二分图最大匹配

匈牙利算法无压力

#include<cstdio>
#include<cstring>
    bool way[201][201];
    int link[201];
    bool used[201];
    int count=0;
    int path(int u);
    int n,m;
    int main(){
        freopen("air.in","r",stdin);
        freopen("air.out","w",stdout);
        int a,b;
        scanf("%d %d",&n,&m);
        m-=n;
        memset(way,false,sizeof(way));
        for(;;){
            scanf("%d %d",&a,&b);
            if(a!=-1&&b!=-1)
                way[a][b-n]=true;
            else
                break;
            }
        memset(link,0,sizeof(link));
        for(int i=1;i<=n;i++){
            memset(used,false,sizeof(used));
            if(path(i))
                count++;
            }
        printf("%d\n",count);
        for(int i=1;i<=m;i++)
            if(link[i])
                printf("%d %d\n",link[i],i+n);
        fclose(stdin);
        fclose(stdout);
        return 0; 
        }
    int path(int u){
        for(int v=1;v<=m;v++)
            if(way[u][v]&&!used[v]){
                used[v]=true;
                if(!link[v]||path(link[v])){
                    link[v]=u;
                    return true;
                    }
                }
        return false;
        }

Dinic全数组版

#include<cstdio>
#include<cstring>
#include<cstdlib>
// max__:数组大小，数据上界的常量
// 大写英文开头:常用小数据结构（Queue\Hash\Father\Stack\Matrix）
// 小写英文：主数据结构(一般是图或平衡树)、单个变量
// 全大写：特殊符号、宏定义
// head点的边表头，Head队列头
//
const int maxn=301;
const int maxm=300001;
const int maxnum=0x7FFFFFFF;
//
int Queue[maxm],Head,Tail;
//
int to[maxm],next[maxm],sc[maxm],snum=0;
int level[maxn],head[maxn],out[maxn];
//
void init();
void insert(int x,int y,int c);
void max_flow(int n,int s,int t);
//
int main(){
freopen("air.in","r",stdin);
freopen("air.out","w",stdout);
int n,m;
scanf("%d %d",&m,&n);
init();
int a,b;
int s=n+1,t=n+2;
for(int i=1;i<=m;i++)
insert(s,i,1);
for(int i=m+1;i<=n;i++)
insert(i,t,1);
for(;scanf("%d %d",&a,&b)!=EOF;)
if(a!=-1)
insert(a,b,1);
else
break;
max_flow(n+2,s,t);
fclose(stdin);
fclose(stdout);
return 0;
}
void init(){
snum=1;//for ^
memset(head,0,sizeof(head));
}
void insert(int x,int y,int c){
snum++;
to[snum]=y;
sc[snum]=c;
next[snum]=head[x];
head[x]=snum;
snum++;
to[snum]=x;
sc[snum]=0;
next[snum]=head[y];
head[y]=snum;
}
void max_flow(int n,int s,int t){
int flow=0,cur;
for(;;){
memset(level,0,sizeof(level));
Head=Tail=1;
level[s]=1;
Queue[Head]=s;
for(;Head<=Tail;Head++){
int t=Queue[Head];
for(int p=head[t];p;p=next[p])
if(sc[p]&&!level[to[p]]){
Tail++;
level[to[p]]=level[t]+1;
Queue[Tail]=to[p];
}
}
if(level[t]==0)break;
for(int i=1;i<=n;i++)out[i]=head[i];
int q=0;
for(;;){
if(!q){
for(cur=out[s];cur;cur=next[cur])
if(sc[cur]&&out[to[cur]]&&level[to[cur]]==2)
break;
if(cur){
q++;
Queue[q]=cur;
out[s]=next[cur];
}
else
break;
}
int u=to[Queue[q]];
if(u==t){
int dd=maxnum;
int ddl=0;
for(int i=1;i<=q;i++)
if(dd>sc[Queue[i]]){
dd=sc[Queue[i]];
ddl=i;
}
flow+=dd;
for(int i=1;i<=q;i++){
sc[Queue[i]]-=dd;
sc[Queue[i]^1]+=dd;
}
for(int i=1;i<=q;i++)
if(!sc[Queue[i]]){
q=ddl-1;
break;
}
}
else{
for(cur=out[u];cur;cur=next[cur])
if(sc[cur]&&out[to[cur]]
&&level[u]+1==level[to[cur]])
break;
if(cur){
q++;
Queue[q]=cur;
out[u]=next[cur];
}
else{
out[u]=0;
q--;
}
}
}
}
printf("%d\n",flow);
memset(level,0,sizeof(level));
Head=Tail=1;
level[s]=1;
Queue[Head]=s;
for(;Head<=Tail;Head++){
int t=Queue[Head];
for(int p=head[t];p;p=next[p]){
if(level[t]==2&&to[p]!=s&&!sc[p])
printf("%d %d\n",t,to[p]);
if(!level[to[p]]){
Tail++;
level[to[p]]=level[t]+1;
Queue[Tail]=to[p];
}
}
}
}

很无奈，自己写了judge

#include<cstdio>
#include<cstdlib>
#include<cstring>
FILE *fscore,*freport,*fstd,*fin,*fout;
int a=1,b=1;
int n,m;
int aa=0,bb=0;
bool way[201][201];
bool usex[201];
bool usey[201];
int score;
void Judge(){
int a,b;
fscanf(fin,"%d %d",&n,&m);
m-=n;
memset(way,false,sizeof(way));
memset(usex,false,sizeof(usex));
memset(usey,false,sizeof(usey));
for(;;){
fscanf(fin,"%d %d",&a,&b);
if(a!=-1&&b!=-1)
way[a][b-n]=true;
else
break;
}
fscanf(fout,"%d",&a);
fscanf(fstd,"%d",&b);
if(a!=b){
fprintf(fscore,"%d",0);
fprintf(freport,"Wrong number of matches\n");
return ;
}
for(int i=a;i>=1;i--){
fscanf(fout,"%d %d",&a,&b);
b-=n;
if(!way[a][b]) {
fprintf(fscore,"%d",score/2);
fprintf(freport,"Wrong match！\n");
return ;
}
if(usex[a]){
fprintf(fscore,"%d",score/2);
fprintf(freport,"Wrong match！\n");
return ;
}
else
usex[a]=false;
if(usey[b]){
fprintf(fscore,"%d",score/2);
fprintf(freport,"Wrong match！\n");
return ;
}
else
usey[b]=false;
}
fprintf(fscore,"%d",score);
}
int main(int argc,char *argv[]){
fscore=fopen("score.log","w");//打开得分文件
freport=fopen("report.log","w");//打开报告文件
fstd=fopen(argv[2],"r");//打开测试点标准输出文件
score=atoi(argv[1]);//取得测试点的分数
fin=fopen("air.in","r");
fout=fopen("air.out","r");
Judge();
fclose(fscore);//关闭得分文件
fclose(freport);//关闭报告文件
return 0;
}