USACO算法系列二十——heritage

    题目：http://www.nocow.cn/index.php/Translate:USACO/heritage

    很简单，知道前序，中序排列，求二叉树的后序排列。递归一下轻松搞定。

#include <iostream>#include <fstream>#include<string.h>#define SIZE 27using namespace std;char pre[SIZE];char middle[SIZE];char last[SIZE];int l = 0;int lastindex = 0;void getLast(int head, int start, int end){for (int i = start; i < end; i ++){if (middle[i] == pre[head]){getLast(head + 1, start, i);getLast(head + i - start +1, i+1, end);last[lastindex] = pre[head];lastindex ++;break;}}}int main(){ifstream fin("heritage.in");ofstream fout("heritage.out");char str[30];fin >> str;l = strlen(str);for (int i=0; i < l; i ++){middle[i] = str[i];}fin >> str;for(int i=0; i <l; i ++){pre[i] = str[i];}getLast(0,0,l);last[l] = '/0';fout<<last <<endl;return 0;} 

      运行结果：

Executing... Test 1: TEST OK [0.011 secs, 3016 KB] Test 2: TEST OK [0.011 secs, 3016 KB] Test 3: TEST OK [0.000 secs, 3016 KB] Test 4: TEST OK [0.011 secs, 3016 KB] Test 5: TEST OK [0.011 secs, 3016 KB] Test 6: TEST OK [0.011 secs, 3016 KB] Test 7: TEST OK [0.011 secs, 3016 KB] Test 8: TEST OK [0.011 secs, 3016 KB] Test 9: TEST OK [0.000 secs, 3016 KB]All tests OK.