卧薪尝胆,厚积薄发。
WC2016 挑战NPC
Date: Mon Mar 18 15:09:17 CST 2019 In Category: NoCategory

Description:

$n$ 个球和 $m$ 个筐,每个筐最多能装 $3$ 个球,每个球都必须放进一个筐中,求最多有几个筐子有不超过 $1$ 个球,以及最终每个球分别在哪个筐子中。
$1\leqslant n\leqslant 100$

Solution:

考虑为什么每个筐只能装 $3$ 个球,要求最多有几个筐有不超过 $1$ 个球,我们可以这样考虑,一个三个点的完全图(三角形)内部最多有一个匹配,而这样一个图最多向外连三个匹配,因此我们可以把每个筐拆三个点,内部连成完全图,然后球和对应的筐的三个点都连边,反正最后也只会连一个,然后求最大匹配,最大匹配 $-$ 球数就是筐内部连的个数,也就是只有不超过一个球的筐的个数。

Code:


#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#include<queue>
#include<cctype>
#include<cstring>
using namespace std;
inline int rd()
{
register int res = 0,f = 1;register char c = getchar();
while(!isdigit(c)){if(c == '-')f = -1;c = getchar();}
while(isdigit(c))res = (res << 1) + (res << 3) + c - '0',c = getchar();
return res;
}
int n,m,p;
#define MAXM 110
#define MAXN 310
#define MAXE (MAXM * 3 + MAXN * MAXN * 3)
#define MAXP (MAXM * 3 + MAXN)
struct edge
{
int to,nxt;
}e[MAXE << 1];
int edgenum = 0;
int lin[MAXP] = {0};
void add(int a,int b)
{
e[++edgenum] = (edge){b,lin[a]};lin[a] = edgenum;
e[++edgenum] = (edge){a,lin[b]};lin[b] = edgenum;
return;
}
int f[MAXP],pre[MAXP],col[MAXP],match[MAXP];
int tag[MAXP],tim = 0;
int find(int x){return (f[x] == 0 ? x : f[x] = find(f[x]));}
int LCA(int u,int v)
{
++tim;
u = find(u);v = find(v);
while(tag[u] != tim)
{
tag[u] = tim;
u = find(pre[match[u]]);
if(v)swap(u,v);
}
return u;
}
queue<int> q;
void blossom(int u,int v,int lca)
{
while(find(u) != lca)
{
pre[u] = v;v = match[u];
if(col[v] == 2)col[v] = 1,q.push(v);
if(find(u) == u)f[u] = lca;
if(find(v) == v)f[v] = lca;
u = pre[v];
}
return;
}
int work(int s)
{
memset(f,0,sizeof(f));
memset(pre,0,sizeof(pre));
memset(col,0,sizeof(col));
while(!q.empty())q.pop();
q.push(s);col[s] = 1;
while(!q.empty())
{
int k = q.front();q.pop();
for(int i = lin[k];i != 0;i = e[i].nxt)
{
int v = e[i].to;
if(find(k) == find(v))continue;
if(col[v] == 2)continue;
if(!col[v])
{
col[v] = 2;pre[v] = k;
if(!match[v])
{
for(int i = v,pr;i;i = pr)
{
pr = match[pre[i]];
match[i] = pre[i];match[pre[i]] = i;
}
return 1;
}
col[match[v]] = 1;
q.push(match[v]);
}
else
{
int lca = LCA(k,v);
blossom(k,v,lca);
blossom(v,k,lca);
}
}
}
return 0;
}
void work()
{
edgenum = 0;
memset(lin,0,sizeof(lin));
memset(match,0,sizeof(match));
scanf("%d%d%d",&n,&m,&p);
for(int i = 1;i <= m;++i)
{
add((i - 1) * 3 + 1 + n,(i - 1) * 3 + 2 + n);
add((i - 1) * 3 + 2 + n,(i - 1) * 3 + 3 + n);
add((i - 1) * 3 + 3 + n,(i - 1) * 3 + 1 + n);
}
int a,b;
for(int i = 1;i <= p;++i)
{
scanf("%d%d",&a,&b);
add(a,(b - 1) * 3 + 1 + n);
add(a,(b - 1) * 3 + 2 + n);
add(a,(b - 1) * 3 + 3 + n);
}
int ans = 0;
for(int i = 1;i <= n + 3 * m;++i)if(!match[i])ans += work(i);
cout << ans - n << endl;
for(int i = 1;i <= n;++i)printf("%d ",(match[i] - n - 1) / 3 + 1);
return;
}
int main()
{
int testcases = rd();
while(testcases--)work();
return 0;
}
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