1156. Binary tree

先序，递归。

#include <iostream>#include <cstring>int tree[1001][2];char rec[1001];using namespace std;void read(int r) {cout << rec[r];for(int i = 0; i < 2; i++) {if(tree[r][i] != 0) {read(tree[r][i]);}}}int main() {int n;while(cin >> n) {memset(tree, 0, sizeof(tree));memset(rec, 0, sizeof(rec));int no, l, r, node[n];char c;for(int i = 0; i < n; i++) {cin >> no >> c >> l >> r;rec[no] = c;tree[no][0] = l;tree[no][1] = r;node[i] = no;}int root = 0;for(int i = 0; i < n; i++) {root = node[i];int only = true;for(int j = 0; j < n; j++) {if(tree[node[j]][0] == root || tree[node[j]][1] == root){only = false;break;}}if(only) {break;}}read(root);cout << endl;}return 0;}