437. Path Sum III

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int count=0;

map<int,int> updataMap(TreeNode* root,int sum)
{
map<int,int> newMap;
if(root==NULL)
return newMap;
else
{
map<int,int> leftMap=updataMap(root->left,sum);
map<int,int> rightMap=updataMap(root->right,sum);

for(map<int,int>::iterator it=leftMap.begin();it!=leftMap.end();it++)
newMap[it->first+root->val]+=it->second;

for(map<int,int>::iterator it=rightMap.begin();it!=rightMap.end();it++)
newMap[it->first+root->val]+=it->second;

newMap[root->val]+=1;

count+=newMap[sum];

return newMap;
}
}

int pathSum(TreeNode* root, int sum) {

map<int,int> result=updataMap(root,sum);

//for(map<int,int>::iterator it=result.begin();it!=result.end();it++)
//       cout<<it->first<<" "<<it->second<<endl;

return count;
}
};