# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1098443 | alexander707070 | Sorting (IOI15_sorting) | C++14 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
#include "sorting.h"
#define MAXN 200007
using namespace std;
int n,m,q,br;
int pos[MAXN],s[MAXN],post[MAXN];
int to[MAXN];
int check(int stop){
for(int i=0;i<n;i++)s[i]=i;
for(int i=0;i<stop;i++)swap(s[X[i]],s[Y[i]]);
for(int i=0;i<n;i++)to[s[i]]=i;
for(int i=0;i<n;i++){
s[i]=S[i]; pos[s[i]]=i;
post[to[i]]=i;
}
int pt=0;
for(int i=0;i<stop;i++){
P[i]=Q[i]=0;
swap(s[X[i]],s[Y[i]]);
swap(to[X[i]],to[Y[i]]);
swap(pos[s[X[i]]],pos[s[Y[i]]]);
swap(post[to[X[i]]],post[to[Y[i]]]);
while(pt<n and to[pos[pt]]==pt)pt++;
if(pt==n)continue;
P[i]=pos[pt]; Q[i]=post[pt];
swap(s[P[i]],s[Q[i]]);
swap(pos[s[P[i]]],pos[s[Q[i]]]);
}
q=stop; br=0;
for(int i=0;i<n;i++){
s[i]=S[i];
if(s[i]==i)br++;
}
for(int i=0;i<stop;i++){
if(br==n)return i;
if(s[X[i]]==X[i])br--;
if(s[Y[i]]==Y[i])br--;
swap(s[X[i]],s[Y[i]]);
if(s[X[i]]==X[i])br++;
if(s[Y[i]]==Y[i])br++;
if(s[P[i]]==P[i])br--;
if(s[Q[i]]==Q[i])br--;
swap(s[P[i]],s[Q[i]]);
if(s[P[i]]==P[i])br++;
if(s[Q[i]]==Q[i])br++;
}
if(br==n)return q;
return -1;
}
int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
n=N; m=M;
int l=-1,r=n,tt;
while(l+1<r){
int tt=(l+r)/2;
if(check(tt)!=-1){
r=tt;
}else{
l=tt;
}
}
return check(r);
}