To solve the problem indexes of the array are also needed to be updated and queried.
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#include <cstdio> #include <vector> #include <cstring> #include <algorithm> #include <iostream> using namespace std; struct RevPrime{ int reversePrime; int factorCount; }; int prime[1000001]; RevPrime arr[80000]; int Bit[2][80000]; vector<int> vb; int k=1; int reverse(int a) { int num=0; while(a) { num*=10; num += (a%10); a/=10; } return num; } bool cmp(RevPrime a,RevPrime b) { return a.reversePrime<b.reversePrime; } void update(int row,int idx,int val) { while(idx<k) { Bit[row][idx]+=val; idx +=(idx & (-idx)); } } int query(int row,int idx) { int ret=0; while(idx>0) { ret+=Bit[row][idx]; idx -= (idx & (-idx)); } return ret; } int binarySearch(int lw,int hi,int val) { if(hi<lw) return 0; int mid = (hi+lw)>>1; if(arr[mid].reversePrime<val) { return binarySearch(mid+1,hi,val); } else if(arr[mid].reversePrime>val) { return binarySearch(lw,mid,val); } else if(arr[mid].reversePrime==val) return mid; return 0; } int findIndex_bianarySearch(int lw,int hi,int modifiedIndex_value) { if(hi<lw) return 0; int mid =(hi+lw)>>1; int mid_val=query(1,mid); if(mid_val<modifiedIndex_value) return findIndex_bianarySearch(mid+1,hi,modifiedIndex_value); else if(mid_val>modifiedIndex_value) return findIndex_bianarySearch(lw,mid,modifiedIndex_value); else return mid; return 0; } int main () { int b; int tmp; for(int i=2;i<1000001;i++) { if(prime[i]==0) { prime[i]+=1; vb.push_back(i); for(int j=i+i;j<1000001;j+=i) { prime[j]+=1; tmp=j/i; while(tmp%i==0) { prime[j]+=1; tmp/=i; } } } } for(int i=0;i<vb.size();i++) { b = reverse(vb[i]); arr[k].factorCount=prime[b]; while(b<1000000) { b*=10; arr[k].factorCount+=2; } arr[k].reversePrime=b; k+=1; } sort(arr,arr+k,cmp); for(int i=1;i<k;i++) { update(0,i,arr[i].factorCount); update(1,i,1); } char ch; int n; while(scanf("%c", &ch)!=EOF) { scanf("%d",&n); if(ch=='q') { int original_index=findIndex_bianarySearch(1,k,n+1); cout<<query(0,original_index)<<"\n"; } if(ch=='d') { int idx = binarySearch(1,k,n); update(0,idx,(-1)*arr[idx].factorCount); update(1,idx,-1); } } return 0; } |