11234 - Expressions*****

/* 题意：根据后缀表达式，输出使用队列实现相同效果的序列 需要用到栈、队列、二叉树 */ //无指针，推荐,可是未通过！！！ #include <iostream> #include <string> #include <stack> #include <queue> #include <cstring> #include <cstdio> using namespace std; const int kMax=10007; struct Node { int parent,left,right; }tree[kMax]; int ans[kMax]; int main() { /* freopen("data.in","r",stdin); freopen("data.out","w",stdout); //*/ int T; scanf("%d",&T); while(T--) { stack<int> s; memset(tree,-1,sizeof(tree)); string line; cin>>line; for(int i=0;i<line.size();i++) { if(islower(line[i])) s.push(i); else { int x,y; y=s.top(); s.pop(); x=s.top(); s.pop(); tree[i].left=x; tree[i].right=y; tree[x].parent=tree[y].parent=i; s.push(i); } } int root; for(int i=0;i<line.size();i++) { if(tree[i].parent==-1) { root=i; break; } } queue<int> q; q.push(root); int u=0; memset(ans,0,sizeof(ans)); while(!q.empty()) { int x=q.front(); q.pop(); ans[u++]=x; if(tree[x].left!=-1) q.push(tree[x].left); if(tree[x].right!=-1) q.push(tree[x].right); } for(int i=u-1;i>=0;i--) printf("%c",line[ans[i]]); printf("\n"); } return 0; } //指针实现，通过 #include <iostream> #include <string> #include <stack> #include <queue> #include <cstring> #include <cstdio> using namespace std; const int kMax=10007; char ans[kMax]; struct TNode { char op; TNode *left,*right; }; TNode *creatTree(char a=0,TNode *lchild=NULL,TNode *rchild=NULL) { TNode *tree=new TNode; tree->left=lchild; tree->right=rchild; tree->op=a; return tree; } int main() { /* freopen("data.in","r",stdin); freopen("data.out","w",stdout); //*/ int T; scanf("%d",&T); while(T--) { stack<TNode *> s; string line; cin>>line; for(int i=0;i<line.size();i++) { if(islower(line[i])) { TNode *tree=creatTree(line[i]); s.push(tree); } else { TNode *l_child,*r_child; r_child=s.top(); s.pop(); l_child=s.top(); s.pop(); TNode *tree=creatTree(line[i],l_child,r_child); s.push(tree); } } TNode *root=s.top(); queue<TNode *> q; q.push(root); int u=0; memset(ans,0,sizeof(ans)); while(!q.empty()) { TNode *tree=q.front(); q.pop(); ans[u++]=tree->op; if(tree->left!=NULL) q.push(tree->left); if(tree->right!=NULL) q.push(tree->right); } for(int i=u-1;i>=0;i--) printf("%c",ans[i]); printf("\n"); } return 0; }