# Passed before but get a TLE now

• I write me c++ solution using stranded union-find with "balance" feature (with a rank). It passed first time. However, after few days when I trying to solve this problem again. I got a TLE at the 1, 10000 test case. I have cope paste some of the top rank post int c++ language. they actually slow than mine. (and also got a TLE). I do not know why? I saw the Java solution with the same idea only takes 15ms.

• I have just relaxed the constraint. Your solution is now accepted. Sorry about that.

• Thanks!
Do you know why Java solutions are so outperform C++ solutions?

• ``````class Solution {
struct Node {
pair<int, int> parent;
int height;
Node():parent(-1,-1), height(1) {}
};
// get_parent node;
inline Node * get_parent (Node** ptable, Node* cur) {
return &ptable[cur->parent.first][cur->parent.second];
}
inline bool is_empty(Node *n) {
return n->parent.first == -1;
}
// find
Node * find(Node** ptable, int i, int j) {
Node * cur = &ptable[i][j];
if (!is_empty(cur)) {
Node * next = cur;
do {
cur = next;
next = get_parent(ptable, cur);
} while (cur != next);
}
return cur;
}
// merge, this should be called when non of the node is (-1,-1)
Node * merge(Node**ptable, Node*n1, Node*n2, int &count) {
if (n1 == n2 || is_empty(n2)) {
return n1;
}
count--;
if (n1->height < n2->height) {
n1->parent = n2->parent;
return n2;
} else if (n1->height > n2->height) {
n2->parent = n1->parent;
return n1;
} else {
n2->height++;
n1->parent = n2->parent;
return n2;
}
}

public:
vector<int> numIslands2(int m, int n, vector<pair<int, int>>& positions) {
Node** ptable = new Node*[m];
for (int i=0; i<m; ++i) {
ptable[i] = new Node[n];
}
vector<int> res;
res.reserve(positions.size());
int count=0;
Node * n1, n2;
for (const pair<int, int> &p : positions) {
int i=p.first;
int j=p.second;
n1 = find(ptable, i, j);
if (!is_empty(n1)) {
res.push_back(count);
continue;
}
count++;
// set to itsefl
n1->parent.first = i;
n1->parent.second = j;

// ^v<>;
if (i>0) n1 = merge(ptable, n1, find(ptable, i-1, j), count);
if (i+1<m) n1 = merge(ptable, n1, find(ptable, i+1, j), count);
if (j>0) n1 = merge(ptable, n1, find(ptable, i, j-1), count);
if (j+1<n) merge(ptable, n1, find(ptable, i, j+1), count);
res.push_back(count);
}

for (int i = 0; i<m; ++i) {
delete [] ptable[i];
}
delete [] ptable;
return res;
}
};``````

• Currently Java measures only the solution time, while C++ measures the entire time, including reading input and writing output. In future we will try to change this to measure only the solution time across all languages.

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