After reading some tutorials on segment tree:
I thought to implement this data structure in Object Oriented methodology whereby I used vector instead of arrays in (contrast with tutorials) approach to hide implementation details, but it verdicts SIGSEGV for size in order of 10^5. But works fine (I hope) for array size less than of 10^4 order;
typedef struct SegmentTree{
vector<int> tree, udp; int orgsize;
/******************BUILD***********************/
SegmentTree(vector<int>& list){ //CONSTRUCTOR
orgsize=list.size();
int size=((int)(pow(2,31-__builtin_clz(orgsize))))<<1;
tree.resize(size); udp.assign(size,0); build(1,0,orgsize-1,list);
}
void build(int cur, int s, int e, vector<int>& list){
if(s==e){ tree[cur]=list[s]; return ;}
else{
int mid=(s+e)/2;
build(cur<<1,s,mid,list); build((cur<<1)+1,mid+1,e,list);
tree[cur]= tree[cur<<1]+tree[(cur<<1)+1]; //NODE FUNCTION
}
}
/*************** UPDATE **************************/
void update(int s, int e, int val){ update(1,0,orgsize-1,s,e,val);}
void update(int cur, int ts, int te, int s, int e, int val){ //ts: temporary start, cur: current
if(ts>=s && te<=e) udp[cur]+=val;
else{
tree[cur]+=(min(te,e)-max(ts,s)+1)*val; //NODE FUNCTION
int mid=(ts+te)/2;
if(mid>=s && ts<=e) update(cur<<1,ts,mid,s,e,val);
if(mid+1<=e && te>=s) update((cur<<1)+1,mid+1,te,s,e,val);
}
}
/*************** QUERY ***************************/
ll query(int s, int e){return q(1,0,orgsize-1,s,e);}
ll q(int cur, int ts,int te, int s, int e){ //ts: temporary start, cur: current
if(ts>=s && te<=e){
if(udp[cur]!=0){
tree[cur]+=(te-ts+1)*udp[cur]; //NODE FUNCTION
if(2*cur < udp.size()){
udp[cur<<1]+=udp[cur];
udp[(cur<<1)+1]+=udp[cur];
}
udp[cur]=0;
}
return tree[cur];
}
else{
tree[cur]+=(te-ts+1)*udp[cur];
if((cur<<1) < udp.size()){
udp[cur<<1]+=udp[cur];
udp[(cur<<1)+1]+=udp[cur];
}
udp[cur]=0;
ll temp=0; int mid=(ts+te)/2;
if(mid>=s && ts<=e) temp+=q(cur<<1,ts,mid,s,e);
if(mid+1<=e && te>=s) temp+=q((cur<<1)+1,mid+1,te,s,e);
return temp;
}
}
} ST;
I tried this program for SPOJ-Horrible and get "Runtime error — SIGSEGV" which then I presume to arise from implementation as when I tried running on 10^5 it shows that error again.
My submission for above mention problem: Ideone
I tried using global vector of the object udp & tree and also the vector which I used to build this segment tree. But it didn't work. Is there a fix or shall I not use this OOP based implementation? Because
Thank you for having time to read this.!
UPD: Its solved! For those who are wondering the source of bug, it was in the calculation of size in constructor changing to 2 << (32 - __builtin_clz(orgsize - 1)) led to Accepted verdict.
