Submission #718523

#	Time	Username	Problem	Language	Result	Execution time	Memory
718523		myrcella	Sorting (IOI15_sorting)	C++17	20 / 100	323 ms	405024 KiB

sorting

//by szh
#include<bits/stdc++.h>
#include <unordered_map>
using namespace std;

#define fi first
#define se second
#define pii pair<int,int>
#define pll pair<long long,long long>
#define pb push_back
#define debug(x) cerr<<#x<<"="<<x<<endl
#define pq priority_queue
#define inf 0x3f
#define rep(i,a,b) for (int i=a;i<(b);i++)
#define MP make_pair
#define SZ(x) (int(x.size()))
#define ll long long
#define mod 1000000007
#define ALL(x) x.begin(),x.end()
void inc(int &a,int b) {a=(a+b)%mod;}
void dec(int &a,int b) {a=(a-b+mod)%mod;}
int lowbit(int x) {return x&(-x);}
ll p0w(ll base,ll p) {ll ret=1;while(p>0){if (p%2ll==1ll) ret=ret*base%mod;base=base*base%mod;p/=2ll;}return ret;}

#include "sorting.h"

const int maxn = 6e5+10;

int n,m;
int a[maxn],b[maxn];
pii ans[maxn];
pii p[maxn];
deque <int> q[maxn];
int id[maxn];
pii pos[maxn];	
map <pii,int> cntt;
vector <pii> nxt1,nxt2;
pii qid[maxn];

void update(int x,int y,int val) {
	if (pos[x].fi!=pos[x].se) {
		pii tmp = {min(pos[x].fi,pos[x].se),max(pos[x].fi,pos[x].se)};
		cntt[tmp]+=val;
		int hi = cntt[tmp];
		if (hi==1) nxt1.pb(tmp);
		else if (hi==2) nxt2.pb(tmp);
	}
	if (pos[y].fi!=pos[y].se) {
		pii tmp = {min(pos[y].fi,pos[y].se),max(pos[y].fi,pos[y].se)};
		cntt[tmp]+=val;
		int hi = cntt[tmp];
		if (hi==1) nxt1.pb(tmp);
		else if (hi==2) nxt2.pb(tmp);
	}
}
 
bool check(int cnt) {
	cntt.clear();
	while (!nxt1.empty())nxt1.pop_back();
	while (!nxt2.empty())nxt2.pop_back();
	rep(i,0,n) {
		while (!q[i].empty()) q[i].pop_back();
		q[i].pb(i);
		id[i] = i;
		b[i] = a[i];
	}
	rep(i,0,cnt) {
		int x=p[i].fi,y=p[i].se;
		q[id[x]].pb(y);
		q[id[y]].pb(x);
		swap(id[x],id[y]);
		qid[i] = {id[x],id[y]};
	}
	rep(i,0,n) {
		pos[q[i].back()].fi = q[i].front();
		pos[a[i]].se = i;
	}
	rep(i,0,n) if (pos[i].fi!=pos[i].se) {
		pii tmp = {min(pos[i].fi,pos[i].se),max(pos[i].fi,pos[i].se)};
		cntt[tmp]++;
		if (cntt[tmp]==2) nxt2.pb(tmp);
		else nxt1.pb(tmp);
	}
	rep(i,0,cnt) {
		int x = p[i].fi,y=p[i].se;
		swap(b[x],b[y]);
		update(b[x],b[y],-1);
		pos[b[x]].se = x,pos[b[y]].se = y;
		update(b[x],b[y],1);
		
		update(q[qid[i].fi].back(),q[qid[i].se].back(),-1);
		q[qid[i].fi].pop_front(),q[qid[i].se].pop_front();
		pos[q[qid[i].fi].back()].fi = q[qid[i].fi].front();
		pos[q[qid[i].se].back()].fi = q[qid[i].se].front();
		update(q[qid[i].fi].back(),q[qid[i].se].back(),1);
		
		pii cur = {0,0};
		while (!nxt2.empty() and cntt[nxt2.back()]!=2) nxt2.pop_back();
		while (!nxt1.empty() and cntt[nxt1.back()]!=1) nxt1.pop_back();
		if (!nxt2.empty()) cur = nxt2.back();
		else if (!nxt1.empty()) cur = nxt1.back();
		x = cur.fi,y=cur.se;
		swap(b[x],b[y]);
		update(b[x],b[y],-1);
		pos[b[x]].se = x,pos[b[y]].se = y;
		update(b[x],b[y],1);
		ans[i] = cur;
		if (cur.fi==cur.se) return true;
		while (!nxt2.empty() and cntt[nxt2.back()]!=2) nxt2.pop_back();
		while (!nxt1.empty() and cntt[nxt1.back()]!=1) nxt1.pop_back();
		if (nxt1.empty() and nxt2.empty()) return true;
	}
	return false;
}
 
int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	n = N,m= M;
    int l=0,r=M;
    rep(i,0,n) a[i] =S[i];
    rep(i,0,M) p[i] = {X[i],Y[i]};
    while (l<r) {
		int mid=l+r>>1;
		if (check(mid)) r = mid;
		else l = mid+1;
	}
	assert(check(l));
	rep(i,0,l) P[i] = ans[i].fi, Q[i] = ans[i].se;
	return l;
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:122:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  122 |   int mid=l+r>>1;
      |           ~^~

• Subtask 1: 8 / 8
• Subtask 2: 12 / 12
• Subtask 3: 0 / 16
• Subtask 4: 0 / 18
• Subtask 5: 0 / 20
• Subtask 6: 0 / 26