URAL 1025. Democracy in danger

problem url: http://acm.timus.ru/problem.aspx?space=1&num=1025

this should be a sorting question, I used tried using binary sort tree to sort the given vote group serials and print the least half(+1) out(I omit the memory cleanup code):

/*
URAL 1025

AC: time:0.001s memory: 259 KB

using linked Binary Sort Tree
*/

#include <cstdio>
#include <iostream>

using namespace std;

typedef struct BSTNode
{
int fornum;
struct BSTNode* lc;
struct BSTNode* rc;

}BSTNode, *BSTTree;

//global vars

BSTTree g_tree = NULL;

int N = 0; //VOTE group number
int minN = 0;
int cnt = 0; //the counter used to count the min vote number
int sum = 0;

void InsertNode(BSTTree* root, int fornum);

void TraverseTree(BSTTree root);

void main()
{
int i= 0;
int curgp = 0; //record current group's size

scanf("%d", &N);
minN = (int)N/2 +1;

for(i=0;i<N;++i)
{
scanf("%d", &curgp);

InsertNode(&g_tree, (int)(curgp/2) + 1);

}

//traverse the tree and calculate the min value

TraverseTree(g_tree);

}

void InsertNode(BSTTree* root, int fornum)
{
if((*root) == NULL)
{
*root = (BSTNode*)malloc(sizeof(BSTNode));

(*root)->lc = (*root)->rc = NULL;
(*root)->fornum = fornum;
}
else
{
if(fornum< (*root)->fornum)
{
InsertNode(&((*root)->lc) , fornum);
}else
{
InsertNode(&((*root)->rc), fornum);
}

}
}

void TraverseTree(BSTTree root)
{
if(cnt>= minN) return;

if(root == NULL) return;

TraverseTree(root->lc);

sum += root->fornum;
++cnt;

if(cnt == minN)
{
printf("%d", sum);
return;
}

TraverseTree(root->rc);

}