【二分图】专题

来源：互联网发布：聚类算法哪几种编辑：程序博客网时间：2024/06/15 21:55

refer：http://blog.csdn.net/hackbuteer1/article/details/7398008

http://poj.org/problem?id=1469

#include <iostream>#include <math.h>#include <algorithm>#include <string.h>#include <stdio.h>using namespace std;bool g[110][310];bool visit[310];int match[310];int p, n;bool dfs(int u){    for(int i = 1; i <= n; i++){        if(g[u][i] && !visit[i]){            visit[i] = true;            if(match[i] == -1 || dfs(match[i])){                match[i] = u;                return true;            }        }    }    return false;}int main(){    int t;    scanf("%d", &t);    while(t--)    {        scanf("%d%d", &p, &n);        for(int i = 1; i <= p; i++){            for(int j = 1; j <= n; j++){                g[i][j] = false;            }        }        for(int i = 1; i <= n; i++)            match[i] = -1;        bool flag = false;        for(int i = 1; i <= p; i++) //input        {            int times;            scanf("%d", ×);            if(times == 0) flag = true;            while(times--){                int a;                scanf("%d", &a);                g[i][a] = true;            }        }        if(!flag){            int ans = 0;            for(int i = 1; i <= p; i++){                memset(visit, false, sizeof(visit));                if(dfs(i)) ans++;            }            if(ans == p) puts("YES");            else puts("NO");        }        else            puts("NO");    }    return 0;}

http://acm.hdu.edu.cn/showproblem.php?pid=2444

#include <iostream>#include <math.h>#include <algorithm>#include <string.h>#include <stdio.h>using namespace std;#define white 1#define black 0#define none -1int n;bool g[220][220];int color[220];bool visite[220];bool DFS(int u){    for(int i = 0; i <= n; i++)    {        if(g[u][i])        {            if(color[i] == none)            {                color[i] = 1 - color[u];                if(DFS(i) == true) return true;            }            else if(color[u] == color[i]) return true;        }    }    return false;}bool isbigr(){    memset(color, -1, sizeof(color));    color[1] = white;    //printf("%d %d", color[1], color[3]);    if(DFS(1)) return true;    return false;}bool match(int u){    for(int i = 1; i <= n; i++)    {        if(g[u][i] && !visite[i])        {            visite[i] = true;            if(color[i] == -1 || match(color[i]))            {                color[i] = u;                return true;            }        }    }    return false;}int main(){    int m;    while(scanf("%d %d", &n, &m) != -1)    {        for(int i = 0; i <= n; i++)            for(int j = 0; j <= n; j++)                g[i][j] = false;        while(m--)        {            int a, b;            scanf("%d %d", &a, &b);            g[a][b] = true;        }        if(isbigr()) puts("No");        else        {            for(int i = 0; i <= n; i++)                color[i] = -1;            int ans = 0;            for(int i = 1; i<= n; i++)            {                memset(visite, false, sizeof(visite));                if(match(i)) ans++;            }            printf("%d\n", ans);        }    }}

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