并查集的几道题（hdu1198）（1232）（1272）（1598）
1232模板题
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1 #include <stdio.h> 2 #include<string.h> 3 int father[1001]; 4 int find(x) 5 { 6 if(x!=father[x]) 7 father[x] = find(father[x]); 8 return father[x]; 9 } 10 void union1(int x,int y) 11 { 12 father[x] = y; 13 } 14 int main() 15 { 16 int i,j,k,n,m,a,b; 17 while(scanf("%d",&n)&&n) 18 { 19 scanf("%d",&m); 20 int num = 0; 21 for(i = 1 ; i <= n ; i++) 22 father[i] = i; 23 for(i = 1 ; i <= m ; i++) 24 { 25 scanf("%d%d",&a,&b); 26 int px = find(a); 27 int py = find(b); 28 if(px!=py) 29 union1(px,py); 30 } 31 for(i = 1; i <= n ; i++) 32 if(father[i]==i) 33 num++; 34 printf("%d\n",num-1); 35 } 36 return 0; 37 }
1272数据貌似挺水
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1 #include <stdio.h> 2 #include<string.h> 3 int father[100001],k[200001]; 4 int find(int x) 5 { 6 if(x!=father[x]) 7 father[x] = find(father[x]); 8 return father[x]; 9 } 10 void union1(int x,int y) 11 { 12 father[x] = y; 13 } 14 int main() 15 { 16 int i,j,a,b,px,py,g,num; 17 while(scanf("%d%d",&a,&b)!=EOF) 18 { 19 if(a==-1&&b==-1) 20 break; 21 if(a==0&&b==0) 22 { 23 printf("Yes\n"); 24 continue; 25 } 26 g = 0; 27 num = 0; 28 k[g++] = a; 29 k[g++] = b; 30 for(i = 1; i <= 100001 ; i++) 31 father[i] = i; 32 int flag = 0; 33 px = find(a); 34 py = find(b); 35 if(px!=py) 36 union1(px,py); 37 while(scanf("%d%d",&a,&b)!=EOF) 38 { 39 if(a==0&&b==0) 40 break; 41 k[g++] = a; 42 k[g++] = b; 43 px = find(a); 44 py = find(b); 45 if(px!=py) 46 father[px] = py; 47 else 48 if(a!=b) 49 flag = 1; 50 } 51 for(i = 0 ; i < g ; i++) 52 if(father[k[i]]==k[i]) 53 num++; 54 if(num>1) 55 flag = 1; 56 if(flag) 57 printf("No\n"); 58 else 59 printf("Yes\n"); 60 } 61 return 0; 62 }
hdu1198用0和1表示四个方向有没有通道 然后用并查集判联通
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1 #include <stdio.h> 2 #include<string.h> 3 int dis[12][4] = {{1,0,1,0},{1,0,0,1},{0,1,1,0},{0,1,0,1},{1,1,0,0},{0,0,1,1},{1,0,1,1},{1,1,1,0},{0,1,1,1},{1,1,0,1},{1,1,1,1}}; 4 int father[3001]; 5 int find(int x) 6 { 7 if(x!=father[x]) 8 father[x] = find(father[x]); 9 return father[x]; 10 } 11 void union1(int x,int y) 12 { 13 father[x] = y; 14 } 15 int main() 16 { 17 int i,j,k,n,m,px,py,x,y; 18 char c[51][51]; 19 while(scanf("%d%d",&m,&n)!=EOF) 20 { 21 if(n<0&&m<0) 22 break; 23 int num = 0; 24 for(i = 1; i <= m ; i++) 25 { 26 getchar(); 27 for(j = 1; j <= n ; j++) 28 c[i][j] = getchar(); 29 } 30 for(i = 1 ; i <= n*m ; i++) 31 father[i] = i; 32 for(i = 1; i <= m ; i++) 33 { 34 for(j = 1 ; j <= n ; j++) 35 { 36 x = c[i][j]-'A'; 37 y = c[i][j+1]-'A'; 38 if(j!=n) 39 if(dis[x][3]==dis[y][2]&&dis[y][2]==1) 40 { 41 px = find((i-1)*n+j); 42 py = find((i-1)*n+j+1); 43 if(px!=py) 44 union1(px,py); 45 } 46 if(i!=m) 47 { 48 y = c[i+1][j]-'A'; 49 if(dis[x][1]==dis[y][0]&&dis[y][0]==1) 50 { 51 px = find((i-1)*n+j); 52 py = find(i*n+j); 53 if(px!=py) 54 union1(px,py); 55 } 56 } 57 } 58 } 59 for(i = 1 ; i <= n*m ; i++) 60 if(father[i]==i) 61 num++; 62 printf("%d\n",num); 63 } 64 return 0; 65 }
hdu1598
这题刚开始用并查集+BFS+优先队列写的 一直WA 感觉是想麻烦了 最后也没做出来 搜到学姐的报告 就仿照着写了写 枚举吧
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1 #include <iostream> 2 #include <stdio.h> 3 #include<string.h> 4 #include<algorithm> 5 #define N 1000001 6 using namespace std; 7 struct node 8 { 9 int u,v,w; 10 }q[1001]; 11 int father[201]; 12 int find(int x) 13 { 14 if(x!=father[x]) 15 father[x] = find(father[x]); 16 return father[x]; 17 } 18 void union1(int x,int y) 19 { 20 father[x] = y; 21 } 22 bool cmpp(struct node a,struct node b) 23 { 24 return a.w<b.w; 25 } 26 int main() 27 { 28 int i,j,k,m,n,u,v,w,o; 29 while(scanf("%d%d",&n,&m)!=EOF) 30 { 31 for(i = 0; i < m ; i++) 32 scanf("%d%d%d",&q[i].u,&q[i].v,&q[i].w); 33 sort(q,q+m,cmpp); 34 scanf("%d", &o); 35 while(o--) 36 { 37 scanf("%d%d",&u,&v); 38 k = N; 39 for(i = 0 ; i < m ; i++) 40 { 41 for(j = 1; j <= n ; j++) 42 father[j] = j; 43 for(j = i; j < m ; j++) 44 { 45 if(find(q[j].u)!=find(q[j].v)) 46 union1(find(q[j].u),find(q[j].v)); 47 if(find(u)==find(v)) 48 { 49 w = q[j].w-q[i].w; 50 51 if(w<k) 52 k = w; 53 break; 54 } 55 } 56 if(j==m) 57 break; 58 } 59 if(k!=N) 60 printf("%d\n",k); 61 else 62 printf("-1\n"); 63 } 64 } 65 return 0; 66 }