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BINARY-TREE-MAXIMUM-PATH-SUM Solution

/*
*  Author: Arpit Bhayani
*  https://arpitbhayani.me
*/
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <climits>
#include <deque>
#include <iostream>
#include <list>
#include <limits>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>

#define ll long long

#define MIN(a, b) a < b ? a : b
#define MAX(a, b) a > b ? a : b

using namespace std;

int i = 0;
char ch;
while((ch = getchar()) != '\n') {
str[i++] = ch;
}
str[i] = '\0';
return i;
}

struct node {
int val;
struct node * left;
struct node *right;
};

struct node * new_node(int val) {
struct node *t = (struct node *) malloc(sizeof(struct node));
t->val = val;
t->left = t->right = NULL;
return t;
}

int max(int a, int b) {
return a > b ? a : b;
}

int _max_sum(struct node * root, int * sum) {
if(root == NULL) {
return 0;
}

int l = _max_sum(root->left, sum);
int r = _max_sum(root->right, sum);

int lr = l + root->val;
int rr = r + root->val;
int s = root->val;
int lrs = l + r + s;

*sum = max(*sum, max(lr, max(rr, max(s, lrs))));
return max(lr, max(rr, s)); // Not considering l + r + s
}

int maxPathSum(struct node * root) {
int sum = INT_MIN;
_max_sum(root, &sum);
return sum;
}

int main(int argc, char *argv[]) {
struct node * root = NULL;

root = new_node(1);
root->left = new_node(2);
root->right = new_node(3);

printf("%d\n", maxPathSum(root));

return 0;
}