Submission #832777

#	Time	Username	Problem	Language	Result	Execution time	Memory
832777		aymanrs	Sorting (IOI15_sorting)	C++14	100 / 100	178 ms	27340 KiB

sorting

#include <bits/stdc++.h>
#include "sorting.h"
using namespace std;
int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	if(is_sorted(S, S+N)) return 0;
	M = min(M, 4*N);
	int p[M], q[M];
	int R, l = 0, r = M-1, m, b = M, cur;
	int cp[N];
	for(int i = 0;i < N;i++) cp[i] = S[i];
	int opt[N], ipt[N], is[N];
	while(l <= r){
		R = 0;
		for(int i = 0;i < N;i++) {
			S[i] = cp[i];
			is[S[i]] = i;
		}
		m = l+r>>1;
		for(int j = 0;j<N;j++) opt[j]=ipt[j]=j;
		for(int j = m;j>=0;j--) {
			swap(ipt[opt[X[j]]], ipt[opt[Y[j]]]);
			swap(opt[X[j]], opt[Y[j]]);
		}
		cur = 0;
		for(int i = 0;i <= m;i++){
			R++;
			swap(is[S[X[i]]], is[S[Y[i]]]);
			swap(S[X[i]], S[Y[i]]);
			swap(ipt[opt[X[i]]], ipt[opt[Y[i]]]);
			swap(opt[X[i]], opt[Y[i]]);
			while(cur < N && is[cur] == ipt[cur])cur++;
			if(cur == N){
				p[R-1] = q[R-1] = 0;
				continue;
			}
			p[R-1] = is[cur];
			q[R-1] = ipt[cur];
			int sipt = S[ipt[cur]];
			swap(S[is[cur]], S[ipt[cur]]);
			swap(is[cur], is[sipt]);
		}
		if(is_sorted(S, S+N)){
			for(int i = 0;i < R;i++) {
				P[i] = p[i];
				Q[i] = q[i];
			}
			b = R;
			r = m-1;
		} else l = m+1;
	}
	return b;
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:18:8: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   18 |   m = l+r>>1;
      |       ~^~

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