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Cod sursa(job #143847)
# include <stdio.h>
# include <math.h>
# define IN "stramosi.in"
# define OUT "stramosi.out"
# define MAXLINE 20
# define MAXCOL 350000
int N,M;
void gaseste(FILE*,int,int);
void solve();
int mat[MAXLINE][MAXCOL];
int parinte(int,int);
int main(){
solve();
return 0;
}
int mylog(int N){
int d=1;
int p=2;
while(p<N){
p*=2;
d++;
}
return d-1;
}
void genStr(const int count) {
int i,dp,j;
for (i = 1, dp = (count + 1) >> 1; dp; ++i, dp >>= 1) {
for(j = 0; j <= count; ++j) {
mat[i][j] = mat[i - 1][mat[i - 1][j]];
}
}
}
void solve(){
FILE *in=fopen(IN,"rt");
FILE *out=fopen(OUT,"wt");
fscanf(in,"%d %d",&N,&M);
register int i,j;
for (i=0;i<mylog(N)+1;i++)
for (j=1;j<=N;j++)
mat[i][j]=-1;
int P,Q;
for (i=1;i<=N;i++)
fscanf(in,"%d",&mat[0][i]);
genStr(N);
for (i=0;i<M;i++){
fscanf(in,"%d %d",&Q,&P);
gaseste(out,P,Q);
}
fclose(out);
fclose(in);
}
void gaseste(FILE* out,int P,int Q){
//omul are id-ul Q
//vreau al P-lea parinte
int i;
//putem avea maxim 2^18 parinti,aproximez la 2^20
int p=Q;
if(P==0)
p=0;
else
for (i=20;i>=0;i--)
if(P & (1 << i ) )
p=mat[p][i];//afla cel de-al 2^i-lea parinte al lui p
fprintf(out,"%d\n",p);
}