// #pragma GCC optimize("O3") // #pragma GCC optimization("Ofast,unroll-loops") // #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt") #include <bits/stdc++.h> using namespace std; #define int long long #define ll long long #define FOR(i, l, r) for (int i = (l); i <= (r); i++) #define FOD(i, r, l) for (int i = (r); i >= (l); i--) #define fi first #define se second #define pii pair<int, int> const ll mod = 1e9 + 7; const int MAXN = 1e6 + 5; const ll oo = 1e18 + 7; const int base = 10; int n, q, W; struct canh{ int u, v, w; }cc[MAXN]; vector<pii> adj[MAXN]; int m; vector<int> euler; int L[MAXN], R[MAXN]; int d[MAXN], h[MAXN]; void dfs(int u, int p){ euler.push_back(u); for(auto [v, w]:adj[u]){ if(v==p) continue; d[v]=d[u]+w; h[v]=h[u]+1; dfs(v, u); euler.push_back(u); } euler.push_back(u); } struct node{ int mi, mx, res1, res2, pos; }st[8*MAXN]; int lz[8*MAXN]; node merge(node a, node b){ node c; if(a.mx>b.mx){ c=a; } else if(a.mx<b.mx){ c=b; } else{ if(a.pos<b.pos){ c=a; } else{ c=b; } } c.mi=min(a.mi, b.mi); c.res1=max({a.res1, b.res1, a.mx-2*b.mi}); c.res2=max({a.res2, b.res2, b.mx-2*a.mi}); return c; } void build(int id, int l, int r){ if(l>=r){ int u=euler[l]; st[id]={d[u], d[u], -oo, -oo, l}; return; } int mid=(l+r)/2; build(id*2, l, mid); build(id*2+1, mid+1, r); st[id]=merge(st[id*2], st[id*2+1]); } void push(int id){ if(lz[id]!=0){ int val=lz[id]; for(auto nid:{id*2, id*2+1}){ st[nid].mi+=val; st[nid].mx+=val; st[nid].res1-=val; st[nid].res2-=val; lz[nid]+=val; } lz[id]=0; } } void update(int id, int l, int r, int i, int j, int val){ if(l>j || r<i){ return; } if(l>=i && r<=j){ st[id].mi+=val; st[id].mx+=val; st[id].res1-=val; st[id].res2-=val; lz[id]+=val; return; } int mid=(l+r)/2; push(id); update(id*2, l, mid, i, j, val); update(id*2+1, mid+1, r, i, j, val); st[id]=merge(st[id*2], st[id*2+1]); } node get(int id, int l, int r, int i, int j){ if(l>j || r<i){ return {oo, -oo, -oo, -oo, 0}; } if(l>=i && r<=j){ return st[id]; } int mid=(l+r)/2; push(id); return merge(get(id*2, l, mid, i, j), get(id*2+1, mid+1, r, i, j)); } signed main() { ios_base::sync_with_stdio(false); cin.tie(NULL); // freopen("test.txt", "r", stdin); // freopen("o2.out", "w", stdout); if(fopen(".inp", "r")){ freopen(".inp", "r", stdin); freopen(".out", "w", stdout); } cin >> n >> q >> W; FOR(i, 1, n-1){ int u, v, w; cin >> u >> v >> w; cc[i]={u, v, w}; adj[u].push_back({v, w}); adj[v].push_back({u, w}); } euler.push_back(0); dfs(1, 0); m=(int)euler.size()-1; FOR(i, 1, m){ int u=euler[i]; // cout << u << ' '; if(L[u]==0){ L[u]=i; } R[u]=i; } build(1, 1, m); int last=0; while(q--){ int d, e; cin >> d >> e; d=(d+last)%(n-1); e=(e+last)%W; d++; auto [u, v, w]=cc[d]; cc[d].w=e; if(h[u]>h[v]) swap(u, v); update(1, 1, m, L[v], R[v], e-w); int pos=st[1].pos; int res1=get(1, 1, m, 1, pos).res1+st[1].mx; int res2=get(1, 1, m, pos, m).res2+st[1].mx; last=max(res1, res2); cout << last << '\n'; } return 0; }

diameter.cpp: In function 'int main()':
diameter.cpp:132:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  132 |         freopen(".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
diameter.cpp:133:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  133 |         freopen(".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~