101 lines
2.2 KiB
C++
101 lines
2.2 KiB
C++
#include <iostream>
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#include <string>
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using namespace std;
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template <class T>
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struct Node{
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T element;
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Node<T>* left;
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Node<T>* right;
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Node() : element(-1), left(nullptr), right(nullptr) {}
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Node(T x) : element(x), left(nullptr), right(nullptr) {}
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};
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template <class T>
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struct Tree{
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Node<T>* root;
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Tree() : root(nullptr) {}
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Tree(Node<T>* x) : root(x) {}
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void inOrder(Node<T>* x){
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if(!x) return;
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inOrder(x->left);
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cout << x->element << " ";
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inOrder(x->right);
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}
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void preOrder(Node<T>* x){
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if(!x) return;
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cout << x->element << " ";
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preOrder(x->left);
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preOrder(x->right);
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}
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void postOrder(Node<T>* x){
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if(!x) return;
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postOrder(x->left);
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postOrder(x->right);
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cout << x->element << " ";
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}
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};
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bool checky(char s){
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if(s == '+' || s == '-' || s == '*' || s == '/') return true;
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return false;
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}
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int checkb(char s){
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if(s == '(') return 1;
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if(s == ')') return -1;
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return 0;
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}
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//[x, y)
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template <class T>
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Node<T>* build(const string& s, const int& x, const int& y){
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if ((y - x) == 1) return new Node<T>(s[x]);
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// 去掉最外层括号
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if (s[x] == '(' && s[y-1] == ')') {
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int cnt = 0; bool ok = true;
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for (int i = x; i < y; i++) {
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if (s[i] == '(') cnt++;
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if (s[i] == ')') cnt--;
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if (cnt == 0 && i < y-1) { ok = false; break; }
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}
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if (ok) return build<T>(s, x+1, y-1);
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}
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// 两次扫描：先 +-，再 */
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for (int pass = 0; pass < 2; pass++) {
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int js = 0;
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for (int i = y-1; i >= x; i--) {
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js += checkb(s[i]);
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if (checky(s[i]) && js == 0) {
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if ((pass == 0 && (s[i] == '+' || s[i] == '-')) ||
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(pass == 1 && (s[i] == '*' || s[i] == '/'))) {
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Node<T>* tmp = new Node<T>(s[i]);
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tmp->right = build<T>(s, i+1, y);
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tmp->left = build<T>(s, x, i);
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return tmp;
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}
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}
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}
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}
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return nullptr;
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}
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int main(){
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string a;
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cin >> a;
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Node<char>* root = build<char>(a, 0, a.size());
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Tree<char> t(root);
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t.preOrder(root);
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cout << endl;
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t.inOrder(root);
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cout << endl;
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t.postOrder(root);
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cout << endl;
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return 0;
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}
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