bzoj4443 小凸玩矩阵

二分+最大check

 1 #include<algorithm>
 2 #include<iostream>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<cstdio>
 6 #include<string>
 7 #include<cmath>
 8 #include<ctime>
 9 #include<queue>
10 #include<stack>
11 #include<map>
12 #include<set>
13 #define rre(i,r,l) for(int i=(r);i>=(l);i--)
14 #define re(i,l,r) for(int i=(l);i<=(r);i++)
15 #define Clear(a,b) memset(a,b,sizeof(a))
16 #define inout(x) printf("%d",(x))
17 #define douin(x) scanf("%lf",&x)
18 #define strin(x) scanf("%s",(x))
19 #define LLin(x) scanf("%lld",&x)
20 #define op operator
21 #define CSC main
22 typedef unsigned long long ULL;
23 typedef const int cint;
24 typedef long long LL;
25 using namespace std;
26 void inin(int &ret)
27 {
28     ret=0;int f=0;char ch=getchar();
29     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=1;ch=getchar();}
30     while(ch>=‘0‘&&ch<=‘9‘)ret*=10,ret+=ch-‘0‘,ch=getchar();
31     ret=f?-ret:ret;
32 }
33 int n,m,k,a[255][255],Max,s,t,ed;
34 int head[1010],next[200020],zhi[200020],cap[200020];
35 void add(int a,int b,int c)
36 {
37     next[++ed]=head[a],head[a]=ed,zhi[ed]=b,cap[ed]=c;
38     next[++ed]=head[b],head[b]=ed,zhi[ed]=a,cap[ed]=0;
39 }
40 queue<int>h;int dis[1010];
41 bool bfs()
42 {
43     Clear(dis,0);
44     dis[s]=1;h.push(s);
45     while(!h.empty())
46     {
47         int x=h.front();h.pop();
48         for(int i=head[x];i;i=next[i])if(cap[i]&&!dis[zhi[i]])
49             dis[zhi[i]]=dis[x]+1,h.push(zhi[i]);
50     }
51     return dis[t];
52 }
53 int dfs(int x,int Max)
54 {
55     if(!Max||x==t)return Max;
56     int ret=0,temp;
57     for(int i=head[x];i;i=next[i])if(cap[i]&&dis[zhi[i]]==dis[x]+1)
58     {
59         temp=dfs(zhi[i],min(Max,cap[i]));
60         ret+=temp,Max-=temp;
61         cap[i]-=temp,cap[i^1]+=temp;
62         if(!Max)return ret;
63     }
64     if(!ret)dis[x]=-1;
65     return ret;
66 }
67 int dinic()
68 {
69     int ret=0;
70     while(bfs())ret+=dfs(s,2147483647);
71     return ret;
72 }
73 bool check(int x)
74 {
75     Clear(head,0);ed=1;
76     re(i,1,n)re(j,1,m)
77         if(a[i][j]<=x)add(i,j+n,1);
78     re(i,1,n)add(s,i,1);
79     re(i,1,m)add(i+n,t,1);
80     int ret=dinic();
81     if(ret>=n-k+1)return 1;
82     return 0;
83 }
84 int main()
85 {
86     inin(n),inin(m),inin(k);s=n+m+1,t=s+1;
87     re(i,1,n)re(j,1,m)inin(a[i][j]),Max=max(Max,a[i][j]);
88     int l=0,r=Max,mid,ans;
89     while(l<=r)
90     {
91         mid=(l+r)>>1;
92         if(check(mid))ans=mid,r=mid-1;
93         else l=mid+1;
94     }
95     printf("%d",ans);
96     return 0;
97 }