题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=3338
题目大意:填数字,使白色区域的值得和等于有值得黑色区域的相对应的值,用网络流来做
题目思路:增加一个源点和汇点,然后左进上出,用源点连左面,容量为相对应的值,汇点连上面,容量是相对应的值,然后左面连空白区域的,容量为8,因为数字为1-9,有下限,但因每个空白必须有值,所以至少为一,所以容量空间为0-8;然后空白区域来连上面,容量同样为8;
#include<iostream> #include<cstring> #include<cstdio> using namespace std; #define INF 999999999 #define maxn 14000 #define RE(x) (x)^1 int head[maxn]; int st,ed;//开始节点,结束节点 struct Edge { int v,next; int val; Edge() {} Edge( int V , int NEXT , int W = 0 ):v(V),next(NEXT),val(W) {} } edge[500000]; int lvl[maxn], gap[maxn]; int cnt_edge; int map[maxn][maxn]; struct gg { int x,y; int val; } row[maxn],col[maxn]; int emp,row_num,col_num; int n,m,T; void Insert_Edge( int u , int v , int flow = 0 ) { edge[cnt_edge] = Edge(v,head[u],flow); head[u] = cnt_edge++; edge[cnt_edge] = Edge(u,head[v]); head[v] = cnt_edge++; } void Init() { cnt_edge = 0; memset(head,-1,sizeof(head)); memset(lvl, 0, sizeof (lvl)); memset(gap, 0, sizeof (gap)); } int dfs(int u, int flow) { if (u==ed) { return flow; } int tf = 0, sf, mlvl = ed-1; for (int i= head[u]; i != -1; i = edge[i].next) { if (edge[i].val > 0) { if (lvl[u] ==lvl[edge[i].v]+1) { sf = dfs(edge[i].v, min(flow-tf, edge[i].val)); edge[i].val -= sf; edge[RE(i)].val += sf; tf += sf; if (lvl[st] >=ed) { return tf; } if (tf == flow) { break; } } mlvl = min(mlvl, lvl[edge[i].v]); } } if (tf == 0) { --gap[lvl[u]]; if (!gap[lvl[u]]) { lvl[st] =ed; } else { lvl[u] = mlvl+1; ++gap[lvl[u]]; } } return tf; } int sap() { int ans = 0; gap[0]=ed; while (lvl[st] <ed) { ans += dfs(st, INF); } return ans; } int print( int tp ) { int ans = 0; int id = tp + row_num+1; for( int i = head[id] ; i != -1 ; i = edge[i].next ) { int v = edge[i].v; if( v <=row_num+1 ) { ans+= edge[i].val; break; } } return ans+1; } int main() { int i,j; char s[15]; //freopen("F://ACMInput/input.txt","r",stdin); while(scanf("%d%d",&n,&m)!=-1) { emp=row_num=col_num=0; for(i=0; i<n; i++) for(j=0; j<m; j++) { scanf("%s",s); if(s[0]=='.') { map[i][j]=++emp; } else { map[i][j]=-1; if(s[4]!='X') { int tp=(s[4]-'0')*100+(s[5]-'0')*10+s[6]-'0'; row[++row_num].x=i; row[row_num].y=j; row[row_num].val=tp; } if(s[0]!= 'X' ) { int tp = (s[0]-'0')*100+(s[1]-'0')*10+s[2]-'0'; col[++col_num].x = i; col[col_num].y = j; col[col_num].val = tp; } } } T=emp+col_num+row_num+2; st=1; ed=T; Init(); for(i=1; i<=row_num; i++) { int pos = i; int x = row[i].x; int y = row[i].y; int cnt_len = 0; for( y=y+1; y <m ; y++ ) { if( map[x][y] != -1 ) { cnt_len++; Insert_Edge(i+1, row_num+ map[x][y]+1,8); } else break; } Insert_Edge(st,pos+1,row[i].val-cnt_len); } for( i = 1 ; i <=col_num ; i++ ) { int pos =i+1+row_num+emp; int x = col[i].x; int y = col[i].y; int cnt_len = 0; for( x=x+1 ; x < n ; x++ ) { if( map[x][y] != -1 ) { cnt_len++; Insert_Edge(row_num+ map[x][y]+1,pos,8); } else break; } Insert_Edge(pos,ed,col[i].val-cnt_len); } sap(); for(i=0; i<n; i++) { for(j=0; j<m; j++) { if(map[i][j]==-1) printf("_ "); else printf("%d ",print(map[i][j])); } printf(" "); } } return 0; }