二叉树非递归遍历

二叉树非递归遍历

代码

include

include

include

include

include

using namespace std;

const int maxn=111;

int n;
int lson[maxn],rson[maxn];
int vis[maxn];

int main(){
scanf("%d",&n);
memset(lson,-1,sizeof(lson));
memset(rson,-1,sizeof(rson));
memset(vis,-1,sizeof(vis));
for(int i=1;i<=n;i++){
int x,y;
scanf("%d%d",&x,&y);
lson[i]=x,rson[i]=y;
}

stack st;

st.push(1);

/* 先序遍历
while(!st.empty()){
int x=st.top();st.pop();
printf("%d ",x);
if(rson[x]>0) st.push(rson[x]);
if(lson[x]>0) st.push(lson[x]);
}

*/

/* 中序遍历
while(!st.empty()){
int x=st.top(); st.pop();
if(vis[x]>-1) printf("%d ",x);
else{
vis[x]=1;
if(rson[x]>0) st.push(rson[x]);
st.push(x);
if(lson[x]>0) st.push(lson[x]);
}
}
*/

/* 后续遍历 */
while(!st.empty()){
int x=st.top(); st.pop();
if(vis[x]>-1) printf("%d ",x);
else{
vis[x]=1;
st.push(x);
if(rson[x]>0) st.push(rson[x]);
if(lson[x]>0) st.push(lson[x]);
}
}

printf("\n");
return 0;
}

/*
7
2 3
4 5
6 7
-1 -1
-1 -1
-1 -1
-1 -1

*/

接一发正经的

include

include

include

using namespace std;

typedef struct node* PBT;
typedef struct node {
int v;
PBT lson;
PBT rson;
node(int v) {
this->v=v;
lson=rson=NULL;
}
} BT;

void PreSearch(PBT root) {
printf("%d ",root->v);
if(root->lson!=NULL) PreSearch(root->lson);
if(root->rson!=NULL) PreSearch(root->rson);
}

void PreSearchNoRecur(PBT root) {
stack st;
st.push(root);
while(!st.empty()) {
PBT p=st.top();
st.pop();
printf("%d ",p->v);
if(p->rson!=NULL) st.push(p->rson);
if(p->lson!=NULL) st.push(p->lson);
}
}

void MidSearch(PBT root) {
if(root->lson!=NULL) MidSearch(root->lson);
printf("%d ",root->v);
if(root->rson!=NULL) MidSearch(root->rson);
}

void MidSearchNoRecur(PBT root){
stack st;
st.push(root);
PBT p=root,cur=root;
while(!st.empty()){
while(cur->lson){
st.push(cur->lson);
cur=cur->lson;
}
PBT p=st.top();
st.pop();
printf("%d ",p->v);
if(p->rson){
st.push(p->rson);
cur=p->rson;
}
}
}

void AftSearch(PBT root) {
if(root->lson!=NULL) AftSearch(root->lson);
if(root->rson!=NULL) AftSearch(root->rson);
printf("%d ",root->v);
}

void AftSearchNoRecur(PBT root){
stack st;
st.push(root);
PBT pre=root;
while(!st.empty()){
PBT p=st.top();
if(prep->lson||prep->rson||(p->lsonNULL&&p->rsonNULL)){
printf("%d ",p->v);
st.pop();
pre=p;
}else{
if(p->rson!=NULL) st.push(p->rson);
if(p->lson!=NULL) st.push(p->lson);
}
}
}

void BuildTree(PBT& root) {
int v;
scanf("%d",&v);
if(v<0) return;
root=new node(v);
BuildTree(root->lson);
BuildTree(root->rson);
}

int main() {
PBT root=NULL;
BuildTree(root);
printf("PreSearch:\n");
PreSearch(root);
printf("\nPreSearchNoRecur:\n");
PreSearchNoRecur(root);
printf("\n\nMidSearch:\n");
MidSearch(root);
printf("\nMidSearchNoRecur:\n");
MidSearchNoRecur(root);
printf("\n\nAftSearch:\n");
AftSearch(root);
printf("\nAftSearchNoRecur:\n");
AftSearchNoRecur(root);
return 0;
}

/*
先序输入(-1代表结点不存在)：
1 3 2 -1 -1 5 -1 -1 4 -1 -1
1 2 3 4 -1 -1 -1 -1 -1
1 2 5 -1 -1 6 -1 -1 3 -1 4 -1 -1
*/