POJ 3422 Kaka's Matrix Travels

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 10000;
18 struct arc{
19     int v,w,f,next;
20     arc(int x = 0,int y = 0,int z = 0,int nxt = 0){
21         v = x;
22         w = y;
23         f = z;
24         next = nxt;
25     }
26 };
27 arc e[maxn*20];
28 int head[maxn],p[maxn],d[maxn],S,T,tot;
29 bool in[maxn];
30 int n,m;
31 queue<int>q;
32 void add(int u,int v,int w,int f){
33     e[tot] = arc(v,w,f,head[u]);
34     head[u] = tot++;
35     e[tot] = arc(u,-w,0,head[v]);
36     head[v] = tot++;
37 }
38 bool spfa(){
39     while(!q.empty()) q.pop();
40     for(int i = S; i <= T; i++){
41         d[i] = INF;
42         in[i] = false;
43         p[i] = -1;
44     }
45     d[S] = 0;
46     in[S] = true;
47     q.push(S);
48     while(!q.empty()){
49         int u = q.front();
50         q.pop();
51         in[u] = false;
52         for(int i = head[u]; ~i; i = e[i].next){
53             if(e[i].f > 0 && d[e[i].v] > d[u] + e[i].w){
54                 d[e[i].v] = d[u] + e[i].w;
55                 p[e[i].v] = i;
56                 if(!in[e[i].v]){
57                     q.push(e[i].v);
58                     in[e[i].v] = true;
59                 }
60             }
61         }
62     }
63     return p[T] > -1;
64 }
65 int solve(){
66     int tmp = 0,minV;
67     while(spfa()){
68         minV = INF;
69         for(int i = p[T]; ~i; i = p[e[i^1].v])
70             minV = min(minV,e[i].f);
71         for(int i = p[T]; ~i; i = p[e[i^1].v]){
72             e[i].f -= minV;
73             e[i^1].f += minV;
74             tmp += minV*e[i].w;
75         }
76     }
77     return tmp;
78 }
79 int main() {
80     int tmp;
81     while(~scanf("%d %d",&n,&m)){
82         S = 0;
83         T = n*n*2 + 1;
84         tot = 0;
85         memset(head,-1,sizeof(head));
86         for(int i = 1; i <= n; i++)
87             for(int j = 1; j <= n; j++){
88                 scanf("%d",&tmp);
89                 add(n*(i-1)+j,n*(i-1)+j+n*n,-tmp,1);
90                 add(n*(i-1)+j,n*(i-1)+j+n*n,0,INF);
91                 if(i < n) add(n*(i-1)+j+n*n,n*i+j,0,INF);
92                 if(j < n) add(n*(i-1)+j+n*n,n*(i-1)+j+1,0,INF);
93             }
94         add(S,1,0,m);
95         add(2*n*n,T,0,m);
96         printf("%d\n",-solve());
97     }
98     return 0;
99 }