二分图最小点覆盖 POJ 1325、2226、3041、3692、3829

POJ 1325

#include <iostream>
#include <algorithm>
#include <vector>
#include <string.h>
#include <cstdio>
using namespace std;
vector<int> ss[105];
int flag[105],visted[105];
bool dfs(int x){
for(int i=0;i<ss[x].size();++i){
if(!visted[ss[x][i]]){
visted[ss[x][i]]=1;
if(flag[ss[x][i]]==-1||dfs(flag[ss[x][i]])){
flag[ss[x][i]]=x;
return true;
}
}
}
return false;
}
int main(){
int n,m,k;
while(scanf("%d",&n)&&n){
scanf("%d%d",&m,&k);
memset(flag,-1,sizeof(flag));
memset(ss,0,sizeof(ss));
int num,x,y;
while(k--){
scanf("%d%d%d",&num,&x,&y);
if(!y)
continue;
ss[x].push_back(y);
}
int sum=0;
for(int i=1;i<=n;++i){
memset(visted,0,sizeof(visted));
if(dfs(i))
sum++;
}
printf("%d\n",sum);
}
return 0;
}

POJ 2226

#include <iostream>
#include <cstdio>
#include <vector>
#include <string.h>
using namespace std;
char map[55][55];
int flag[1002],visted[1002];
vector<int> ss[1002];
int aa[1002][1002],bb[1002][1002];
int r,c;
void chushihua(){
for(int icnt=1,i=1;i<=r;++i){
for(int j=1;j<=c;++j){
if(map[i][j]=='*')
{aa[i][j]=icnt;}
if(map[i][j]=='*'&&map[i][j+1]!='*')
icnt++;
}
}
for(int jcnt=1,i=1;i<=c;++i){
for(int j=1;j<=r;++j){
if(map[j][i]=='*')
{ bb[j][i]=jcnt;}
if(map[j][i]=='*'&&map[j+1][i]!='*')
jcnt++;
}
}
for(int i=1;i<=r;++i){
for(int j=1;j<=c;++j){
if(map[i][j]=='*')
{ss[aa[i][j]].push_back(bb[i][j]);}
}
}
}
bool dfs(int x){
for(int i=0;i<ss[x].size();++i){
if(!visted[ss[x][i]]){
visted[ss[x][i]]=1;
if(!flag[ss[x][i]]||dfs(flag[ss[x][i]])){
flag[ss[x][i]]=x;
return true;
}
}
}
return false;
}
int main(){
//int r,c;
while(~scanf("%d%d",&r,&c)){
memset(map,'0',sizeof(map));
memset(aa,0,sizeof(aa));
memset(bb,0,sizeof(bb));
memset(ss,0,sizeof(ss));
for(int i=1;i<=r;++i){
for(int j=1;j<=c;++j)
cin>>map[i][j];
}
chushihua();
memset(flag,0,sizeof(flag));
int sum=0;
for(int i=1;i<1002;++i){
memset(visted,0,sizeof(visted));
if(dfs(i))
sum++;
}
printf("%d\n",sum);
}
return 0;
}

POJ 3041

#include <iostream>
#include <algorithm>
#include <vector>
#include <string.h>
#include <cstdio>
using namespace std;
vector<int> ss[505];
int flag[505],visted[505];
bool dfs(int x){
for(int i=0;i<ss[x].size();++i){
if(!visted[ss[x][i]]){
visted[ss[x][i]]=1;
if(!flag[ss[x][i]]||dfs(flag[ss[x][i]])){
flag[ss[x][i]]=x;
return true;
}
}
}
return false;
}
int main(){

int n,m;
while(~scanf("%d %d",&n,&m)){
memset(ss,0,sizeof(ss));
memset(flag,0,sizeof(flag));

int x,y;
while(m--){
scanf("%d %d",&x,&y);
ss[x].push_back(y);
}
int sum=0;
for(int i=1;i<=n;++i){
memset(visted,0,sizeof(visted));
if(dfs(i))
sum++;
}
printf("%d\n",sum);
}
return 0;
}

POJ 3692

#include <iostream>
#include <vector>
#include <cstdio>
#include <string.h>
using namespace std;
vector<int> ss[202];
int flag[202],visted[202],map[202][202];
bool dfs(int x){
for(int i=0;i<ss[x].size();++i){
if(!visted[ss[x][i]]){
visted[ss[x][i]]=1;
if(flag[ss[x][i]]==-1||dfs(flag[ss[x][i]])){
flag[ss[x][i]]=x;
return true;
}
}
}
return false;
}
int main(){
int numg,numb,m;
int count=1;
while(scanf("%d%d%d",&numg,&numb,&m)&&numg&&numb&&m){
memset(flag,-1,sizeof(flag));
memset(ss,0,sizeof(ss));
memset(map,0,sizeof(map));
int x,y;
while(m--){
scanf("%d%d",&x,&y);
map[x][y]=1;
}
for(int i=1;i<=numg;++i){
for(int j=1;j<=numb;++j){
if(!map[i][j])
ss[i].push_back(j);
}
}
int sum=0;
printf("Case %d: ",count);
for(int i=1;i<=numg;++i){
memset(visted,0,sizeof(visted));
if(dfs(i))
sum++;
}
printf("%d\n",numg+numb-sum);
count++;
}
return 0;
}

POJ 3829

#include <iostream>
#include <cstdio>
#include <string.h>
#include <vector>
using namespace std;
struct people{
char ch1,ch2;
int x,y;
}aa[505];
vector<int> ss[505];
int visted[505],flag[505],panduan[505];
bool dfs(int x){
for(int i=0;i<ss[x].size();++i){
if(!visted[ss[x][i]]){
visted[ss[x][i]]=1;
if(!flag[ss[x][i]]||dfs(flag[ss[x][i]]))
{flag[ss[x][i]]=x;/*panduan[ss[x][i]]=1;panduan[x]=1;*/return true;}
}
}
return false;
}
int main(){
//freopen("1.txt","r",stdin);
int n,m,p;
while(scanf("%d%d%d",&n,&m,&p)!=EOF){
memset(ss,0,sizeof(ss));
for(int i=1;i<=p;++i){
cin>>aa[i].ch1>>aa[i].x>>aa[i].ch2>>aa[i].y;
}
for(int i=1;i<=p;++i){
for(int j=1;j<=p;++j){
if(aa[i].ch1==aa[j].ch2&&aa[i].x==aa[j].y)
{ ss[i].push_back(j);ss[j].push_back(i);}
}
}
memset(flag,0,sizeof(flag));
memset(panduan,0,sizeof(panduan));
int num=0;
for(int i=1;i<=p;++i){
memset(visted,0,sizeof(visted));
//if(!panduan[i])
if(dfs(i))
{/*printf("i===%d\n",i);printf("size===%d\n",ss[i].size());*/ num++;}
}
printf("%d\n",p-num/2);
}
return 0;
}