hdu 2444 交叉染色判断二分图+二分最大匹配

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/*1A 31ms*/#include<stdio.h>#include<string.h>#define N 300int n;struct node {int u,v,next;}bian[N*N*2];int color[N],vis[N],link[N],visit[N],ma[N][N],f[N],head[N],yong;void addedge(int u,int v) {bian[yong].u=u;bian[yong].v=v;bian[yong].next=head[u];head[u]=yong++;}void init() {//初始化    memset(ma,0,sizeof(ma));    memset(f,0,sizeof(f));    memset(visit,0,sizeof(visit));    memset(link,-1,sizeof(link));    memset(color,0,sizeof(color));    memset(vis,0,sizeof(vis));    memset(head,-1,sizeof(head));    yong=0;}int ff(int u) {//二分匹配int i;for(i=1;i<=n;i++)    if(visit[i]==0&&ma[u][i]) {        visit[i]=1;        if(link[i]==-1||ff(link[i])) {            link[i]=u;            return 1;        }    }    return 0;}int find(int u,int f) {//交叉染色判定int i;for(i=head[u];i!=-1;i=bian[i].next) {    int v=bian[i].v;    if(f)       ma[u][v]=1;//建立邻接矩阵    else        ma[v][u]=1;    if(!vis[v]) {        color[v]=!color[u];        vis[v]=1;        find(v,f^1);    }    else        if(color[v]==color[u])return 0;}return 1;}int main() {    int m,i,a,b,ok;    while(scanf("%d%d",&n,&m)!=EOF) {            init();        while(m--) {            scanf("%d%d",&a,&b);            addedge(a,b);            addedge(b,a);            f[a]=f[b]=1;//存在        }        ok=0;    for(i=1;i<=n;i++)        if(!vis[i]&&f[i]) {            color[i]=1;            vis[i]=1;            if(find(i,1)==0)                ok=1;        }        if(ok) {//是否存在不能交叉染色的            printf("No\n");            continue;        }      b=0;for(i=1;i<=n;i++) {//二分最大匹配    memset(visit,0,sizeof(visit));    b+=ff(i);}printf("%d\n",b);    }return 0;}
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