Using unordered map with custom hash mentioned below for storing frquency/kind of prefix sum but gives TLE and using map gets accepted.
For the first time I have seen unordered map with this custom hash is getting TLE because of it.
(Custom hash from blog )
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
void solve()
{
long long n;cin>>n;
long long a[n];f(n)cin>>a[i];
unordered_map<long long,long long,custom_hash>lp;
lp[0]++;
long long s=0;long long ans=0;
f(n){
s+=a[i];
if(lp[s]>0){ans++;s=0;lp.clear();lp[0]++;}
else lp[s]++;
}cout<<ans<<endl;
}
Can anyone please explain it
