int maxPathSum(TreeNode *root) {
// write your code here
if (!root) return 0;
ans = -0x7fffff;
solve_dp(root);
return ans;
}
int solve_dp(TreeNode *root) {
if(root == NULL)
return 0;
int sum = root->val;
int lf = 0, rt = 0;
if(root->left)
lf = solve_dp(root->left);
if(root->right)
rt = solve_dp(root->right);
if(lf > 0)
sum += lf;
if(rt > 0)
sum += rt;
ans = max(ans, sum);
return max(0, max(lf, rt))+root->val;
}
static int solve_dp(char s1[], char s2[], int len1, int len2){
callcount++;
if (len1 == 0 || len2 == 0)
return 0;
if (s1[len1 - 1] == s2[len2 - 1]){
if (cache[len1][len2] == -1)
cache[len1][len2] = 1 + solve_dp(s1, s2, len1 - 1, len2 - 1);
printf("%c(%d)[%d,%d] ", s1[len1 - 1], cache[len1][len2], len1, len2);
return cache[len1][len2];
}
else{
if (cache[len1 - 1][len2] == -1)
cache[len1 - 1][len2] = solve_dp(s1, s2, len1 - 1, len2);
if (cache[len1][len2 - 1] == -1)
cache[len1][len2 - 1] = solve_dp(s1, s2, len1, len2 - 1);
// guess why MAX here !!!
return max(cache[len1 - 1][len2], cache[len1][len2 - 1]);
}
}
void dp_lcs(void){
int r;
int l1, l2;
// naive
callcount = 0;
r = solve_naive(s1, s2, L1, L2);
printf("common=%d, callcnt=%d\n", r, callcount);
// DP
for (l1 = 0; l1 <= L1; l1++)
for (l2 = 0; l2 <= L2; l2++)
cache[l1][l2] = -1;
callcount = 0;
r = solve_dp(s1, s2, L2, L2);
printf("common=%d, callcnt=%d\n", r, callcount);
br = 1;
return;
}