#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#define dbg(...) printf(__VA_ARGS__);
#define getchar_unlocked getchar
#else
#define dbg(...)
#endif
#define sf scanf
#define pf printf
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)x.size()
#define mnto(x,y) x=min(x,(__typeof__(x))y)
#define mxto(x,y) x=max(x,(__typeof__(x))y)
#define INF 1023456789
#define LINF 2023456789123456789
#define all(x) x.begin(), x.end()
#define disc(x) sort(all(x));x.resize(unique(all(x))-x.begin());
typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef pair<ll,int> li;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
typedef tuple<int, int, int, int> iiii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<pll> vll;
mt19937 rng(time(0));
#define mod 1000000007
inline int add(int a,int b){
int r=a+b;
while(r>=mod)r-=mod;
while(r<0)r+=mod;
return r;
}
inline int mult(int a,int b){
return (int)(((ll)(a*b))%mod);
}
inline int rd(){
int x=0;
char ch=getchar_unlocked();
while(!(ch&16))ch=getchar();//keep reading while current character is whitespace
while(ch&16){//this will break when ‘\n’ or ‘ ‘ is encountered
x=(x<<3)+(x<<1)+(ch&15);
ch=getchar_unlocked();
}
return x;
}
#define maxn 100005
struct edge{
int u,v;ll w;
vector<int> comp;
vector<ii> range;
};
struct node{
int s,e,m;
li v;ll lz;
node *l,*r;
node(int _s,int _e){
s=_s;e=_e;m=(s+e)/2;lz=0;v={0,s};
if(s!=e)l=new node(s,m),r=new node(m+1,e);
}
void ppo(){
v.fi+=lz;
if(s!=e)l->lz+=lz,r->lz+=lz;
lz=0;
}
void up(int x,int y,ll nv){
if(s==x&&e==y){lz+=nv;return;}
if(y<=m)l->up(x,y,nv);
else if(x>m)r->up(x,y,nv);
else l->up(x,m,nv),r->up(m+1,y,nv);
l->ppo();r->ppo();
v=max(l->v,r->v);
}
};
struct tree{
int s,e;
node *root;
vector<ii> ranges;
tree(int _s,int _e){
s=_s;e=_e;
root=new node(s,e);
ranges.resize(e-s+1);
}
void up(int x,int y,ll nv){
root->up(x,y,nv);
}
ll qry(){
root->ppo();
ll ans=root->v.fi;
int i=root->v.se;
root->up(ranges[i].fi,ranges[i].se,-LINF);
if(root->v.fi>=0)ans+=root->v.fi;
up(ranges[i].fi,ranges[i].se,LINF);
return ans;
}
}*root[maxn];
int n,q,sub[maxn];ll w;
bool mark[maxn];
vii AL[maxn];
vector<edge> edges;
void find_sz(int u,int p){
sub[u]=1;
for(auto[v,i]:AL[u]){
if(mark[v]||v==p)continue;
find_sz(v,u);
sub[u]+=sub[v];
}
}
int cnt;
vii ranges;
ii dfs(int u,int p,int c){
ii range={cnt,cnt};++cnt;
for(auto[v,i]:AL[u]){
if(mark[v]||v==p)continue;
ii res=dfs(v,u,c);
edges[i].comp.pb(c);
edges[i].range.pb(res);
mxto(range.se,res.se);
if(p==-1)ranges.pb(res);
}
return range;
}
void decomp(int u){
find_sz(u,-1);
int c=u;
int cnt=0;
while(true){
++cnt;
bool val=true;
for(auto[v,i]:AL[u]){
if(!mark[v]&&sub[v]<sub[c]&&sub[v]>sub[u]/2){
c=v;val=false;break;
}
}
if(val)break;
if(cnt>n)return 1;
}
cnt=0;
ranges.clear();
dfs(c,-1,c);
root[c]=new tree(0,cnt-1);
for(int i=0;i<sz(ranges);++i){
for(int j=ranges[i].fi;j<=ranges[i].se;++j){
root[c]->ranges[j]=ranges[i];
}
}
mark[c]=true;
for(auto[v,i]:AL[c]){
if(!mark[v])decomp(v);
}
}
int main(){
sf("%d%d%lld",&n,&q,&w);
for(int i=0;i<n-1;++i){
int a,b;ll c;
sf("%d%d%lld",&a,&b,&c);
AL[a].pb({b,i});
AL[b].pb({a,i});
edges.pb({a,b,c,{},{}});
}
decomp(1);
for(edge &e:edges){
for(int i=0;i<sz(e.comp);++i){
ii rng=e.range[i];
root[e.comp[i]]->up(rng.fi,rng.se,e.w);
}
}
set<li> s;
for(int i=1;i<=n;++i){
s.insert({root[i]->qry(),i});
}
ll ans=0;
for(int i=0;i<q;++i){
int idx;ll nw;
sf("%d%lld",&idx,&nw);
idx=(idx+ans)%(n-1);
nw=(nw+ans)%w;
edge &e=edges[idx];
ll ow=e.w;
e.w=nw;
//dbg("upd: %d %lld\n",idx,nw);
for(int i=0;i<sz(e.comp);++i){
ii rng=e.range[i];
int c=e.comp[i];
ll old=root[c]->qry();
root[c]->up(rng.fi,rng.se,nw-ow);
ll upd=root[c]->qry();
s.erase(s.find({old,c}));
s.insert({upd,c});
}
ans=(*--s.end()).fi;
pf("%lld\n",ans);
}
}
Compilation message
diameter.cpp: In function 'void decomp(int)':
diameter.cpp:156:19: error: return-statement with a value, in function returning 'void' [-fpermissive]
156 | if(cnt>n)return 1;
| ^
diameter.cpp: In function 'int main()':
diameter.cpp:179:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
179 | sf("%d%d%lld",&n,&q,&w);
| ^
diameter.cpp:182:5: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
182 | sf("%d%d%lld",&a,&b,&c);
| ^
diameter.cpp:205:5: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
205 | sf("%d%lld",&idx,&nw);
| ^
