输入从根节点开始的路径，输出层次遍历的结果
样例输入
（3，L）
（2，R）
（）
输出：
1 3 2
指针实现
1 #include<cstdio> 2 #include<cstring> 3 #include<string.h> 4 #include<stdlib.h> 5 using namespace std; 6 const int maxn=100; 7 char s[maxn]; 8 int fail=0; 9 typedef struct tnode 10 { 11 int have_val; 12 int u; 13 tnode *right,*left; 14 }node; 15 node *root; 16 int cnt,ans[maxn]; 17 node *newnode() 18 { 19 node *r=(node *)malloc(sizeof(node)); 20 r->have_val=0; 21 r->left=r->right=NULL; 22 } 23 void addnode(int u,char *s) 24 { 25 int len=strlen(s); 26 node *r=root; 27 for(int i=0;i<len-1;i++) 28 { 29 if(s[i]=='L') 30 { 31 if(r->left==NULL) 32 r->left=newnode(); 33 r=r->left; 34 } 35 else if(s[i]=='R') 36 { 37 if(r->right==NULL) 38 r->right=newnode(); 39 r=r->right; 40 } 41 } 42 if(r->have_val) 43 fail=1; 44 r->have_val=1; 45 r->u=u; 46 } 47 int bfs() 48 { 49 int rear=1; 50 int front=0; 51 node *q[maxn]; 52 q[0]=root; 53 while(front<rear) 54 { 55 node *r; 56 r=q[front++]; 57 if(r->have_val==0) 58 return 0; 59 ans[cnt++]=r->u; 60 if(r->left!=NULL) 61 q[rear++]=r->left; 62 if(r->right!=NULL) 63 q[rear++]=r->right; 64 } 65 return 1; 66 } 67 void remove(node *u) 68 { 69 if(u==NULL) 70 return ; 71 remove(u->left); 72 remove(u->right); 73 free(u); 74 } 75 int main() 76 { 77 fail=0; 78 remove(root); 79 root=newnode(); 80 root->have_val=1; 81 root->u=1; 82 cnt=0; 83 while(scanf("%s",s)==1) 84 { 85 if(!strcmp(s,"()")) 86 break; 87 int v; 88 sscanf(&s[1],"%d",&v); 89 addnode(v,strchr(s,',')+1); 90 } 91 if(bfs()) 92 { 93 for(int i=0;i<cnt;i++) 94 printf("%d ",ans[i]); 95 printf(" "); 96 97 } 98 else printf("the tree is incorrect "); 99 return 0; 100 }
数组实现
1 #include<cstdio> 2 #include<cstring> 3 #include<string.h> 4 using namespace std; 5 const int maxn=100; 6 int fail=0; 7 int left[maxn],right[maxn],ans[maxn],pos[maxn],vis[maxn]; 8 char s[maxn]; 9 const int root=1; 10 int cnt; 11 void newtree(){cnt=1;left[root]=right[root]=0;} 12 int newnode(){int u=++cnt;left[u]=right[u]=0;return u;}; 13 void addnode(int u,char *s) 14 { 15 int len=strlen(s); 16 int r=1; 17 for(int i=0;i<len-1;i++) 18 { 19 if(s[i]=='L') 20 { 21 if(left[r]==0) 22 left[r]=newnode(); 23 r=left[r]; 24 25 } 26 else if(s[i]=='R') 27 { 28 if(right[r]==0) 29 right[r]=newnode(); 30 r=right[r]; 31 } 32 33 } 34 if(vis[r]) 35 fail=1; 36 pos[r]=u; 37 vis[r]=1; 38 } 39 int bfs() 40 { 41 int front=0,rear=1; 42 int r=1; 43 int q[maxn]; 44 q[0]=1; 45 cnt=0; 46 while(front<rear) 47 { 48 r=q[front++]; 49 if(!vis[r]) 50 return 0; 51 ans[cnt++]=pos[r]; 52 53 if(left[r]) 54 q[rear++]=left[r]; 55 if(right[r]) 56 q[rear++]=right[r]; 57 } 58 return 1; 59 60 } 61 int main() 62 { 63 64 memset(vis,0,sizeof(vis)); 65 fail=0; 66 cnt=0; 67 pos[1]=1; 68 vis[1]=1; 69 newtree(); 70 while(scanf("%s",s)) 71 { 72 if(!strcmp(s,"()")) 73 break; 74 int v; 75 sscanf(&s[1],"%d",&v); 76 addnode(v,strchr(s,',')+1); 77 } 78 79 80 if(bfs()) 81 { 82 83 for(int i=0;i<cnt;i++) 84 printf("%d ",ans[i]); 85 printf(" "); 86 } 87 else printf("the tree is not correct"); 88 return 0; 89 }