UVa 112 - Tree Summing

#include <cstdio>
#include <cstring>
#include <vector>
#include <cctype>

using namespace std;

struct Node
{
Node *left, *right;
int value;
Node()
{
left = right = NULL;
}
};

Node *Creat();
void DFS(Node *root, int add);

vector<int> sum;
int nextNum;

int main()
{
freopen("input.txt", "r", stdin);
int number;
int i, end = 0;
bool flag;
char ch;
scanf("%d", &number);       //只读取第一组输入. 以后的number都靠nextNum来赋值了.
while (true)
{
sum.clear();
flag = false;
Node *root = Creat();
while ((ch = getchar()) != '\n');   //到达当前输入的最后一位, 此时往下读取要么是数字, 要么是EOF
if (scanf("%d", &nextNum) == EOF)
end = 1;
if (root == NULL)       //如果是空的数, 从头开始, 如果是最后一组输入, 必须在此结束. 不然就死循环.
{
printf("no\n");
if (end == 1)
break;
else
continue;
}
DFS(root, 0);
for (i = 0; i < sum.size(); i++)
{
if (sum[i] == number)
{
flag = true;
printf("yes\n");
break;
}
}
if (flag == false)
printf("no\n");
if (end == 1)
break;
number = nextNum;
}
return 0;
}

Node *Creat()
{
char ch;
int temp;
Node *root;
while ((ch = getchar()) != '(');
if (ch == '(')
{
if (scanf("%d", &temp) != 1)
return NULL;
else
{
root = new Node();
root->value = temp;
root->left = Creat();
root->right = Creat();
}
return root;
}
}

void DFS(Node *root, int add)
{
if (!root->left && !root->right)
{
sum.push_back(add + root->value);
return;
}
else
{
//printf("%d ", root->value);
if (root->left)
DFS(root->left, add + root->value);
if (root->right)
DFS(root->right, add + root->value);
}
}