hdu 1710 Binary Tree Traversals

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
const int maxn = 1111;
struct abc
{
int left, right, date;
}node[maxn];
int xian[maxn], zhong[maxn];
int fxian[maxn], fzhong[maxn];
int flag[maxn];
int ans[maxn];
int sum, uu;
void gettree(int ll, int rr, int fn)//ll和rr表示的是中序的区间
{
int i, maxn = -99999999, minn = 99999999;
//minn maxn为中序ll到rr这段区间在先序的区间
for (i = ll; i <= rr; i++)
{
if (fxian[zhong[i]] > maxn) maxn = fxian[zhong[i]];
if (fxian[zhong[i]] < minn) minn = fxian[zhong[i]];
}

//中序ll到rr这段区间的节点为对应的先序序列中的第一个
node[fn].date = xian[minn];

//这段区间的节点在中序的位置
int yy = fzhong[xian[minn]];

//构造左子树
if (yy - ll != 0)
{
sum++;
node[fn].left = sum;
gettree(ll, yy - 1, sum);
}

//构造右子树
if (rr - yy != 0)
{
sum++;
node[fn].right = sum;
gettree(yy + 1, rr, sum);
}

}
void dfs(int wei)//后序遍历 先遍历左儿子 再遍历右儿子 最后遍历节点
{
//遍历左儿子
if (node[wei].left == -1) flag[node[wei].left] = 1;
else
{

dfs(node[wei].left);
if (flag[node[wei].left] == 0) ans[uu] = node[node[wei].left].date, uu++;
flag[node[wei].left] = 1;

}
//遍历右儿子
if (node[wei].right == -1) flag[node[wei].right] = 1;
else
{

dfs(node[wei].right);
if (flag[node[wei].right] == 0) ans[uu] = node[node[wei].right].date, uu++;
flag[node[wei].right] = 1;

}
//遍历节点
flag[wei] = 1;
ans[uu] = node[wei].date, uu++;

}
int main()
{
int n, i;
while (~scanf("%d", &n))
{
sum = 1; uu = 0;
memset(flag, 0, sizeof(flag));
for (i = 0; i <= maxn - 10; i++) node[i].date = -1, node[i].left = -1, node[i].right = -1;
for (i = 1; i <= n; i++) scanf("%d", &xian[i]);
for (i = 1; i <= n; i++) scanf("%d", &zhong[i]);
for (i = 1; i <= n; i++){fxian[xian[i]] = i; fzhong[zhong[i]] = i;}
gettree(1, n, 1);
dfs(1);
for (i = 0; i < uu; i++)
{
if (i<uu-1) printf("%d ", ans[i]);
else printf("%d\n", ans[i]);
}
}
return 0;
}