Check out example codes for "how to find sum of values on path in atree". It will help you in understanding the concepts better.

Code Example 1

``````#include <bits/stdc++.h>
#define FOR(i, x, y) for (int i = x; i < y; i++)
typedef long long ll;
using namespace std;

int n, m;

vector<int> graph[100001];
int timer = 1, tin[100001], tout[100001];
int anc[100001][18];

void dfs(int node = 1, int parent = 0) {
anc[node][0] = parent;
for (int i = 1; i < 18 && anc[node][i - 1]; i++)
anc[node][i] = anc[anc[node][i - 1]][i - 1];

tin[node] = timer++;
for (int i : graph[node]) if (i != parent) dfs(i, node);
tout[node] = timer;
}

int bit[100001];

void update(int pos, int val) { for (; pos <= n; pos += (pos & (-pos))) bit[pos] += val; }

int query(int pos) {
int ans = 0;
for (; pos; pos -= (pos & (-pos))) ans += bit[pos];
return ans;
}

int find_ancestor(int node) {
int lca = node;
for (int i = 17; ~i; i--) {
if (anc[lca][i] && query(tin[anc[lca][i]]) == query(tin[node])) lca = anc[lca][i];
}
return lca;
}

int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
freopen("disconnect.in", "r", stdin);
freopen("disconnect.out", "w", stdout);
cin >> n >> m;
FOR(i, 1, n) {
int a, b;
cin >> a >> b;
graph[a].push_back(b);
graph[b].push_back(a);
}
dfs();

int v = 0;
while (m--) {
int t, x, y;
cin >> t >> x >> y;
int a = x ^ v, b = y ^ v;

if (t == 1) {
if (anc[b][0] == a) swap(a, b);
update(tin[a], 1);
update(tout[a], -1);
} else {
if (find_ancestor(a) == find_ancestor(b)) {
cout << "YES\n";
v = a;
} else {
cout << "NO\n";
v = b;
}
}
}
return 0;
}``````

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