Submission #170914

#	Time	Username	Problem	Language	Result	Execution time	Memory
170914		socho	Sorting (IOI15_sorting)	C++14	20 / 100	53 ms	632 KiB

sorting

#include "sorting.h"
#include "bits/stdc++.h"
using namespace std;

const int MXN = 200005;
int n, m;
int seq[MXN];
vector<pair<int, int> > plan;
vector<pair<int, int> > ans;

bool works(int sw) {
	// cout << "try: " << sw << endl;
	ans.clear();
	int nsw[n];
	for (int i=0; i<n; i++) nsw[i] = seq[i];
	int where[n];
	for (int i=0; i<sw; i++) {
		int a = plan[i].first, b = plan[i].second;
		swap(nsw[a], nsw[b]);
	}
	for (int i=0; i<n; i++) {
		// cout << nsw[i] << ' ';
		where[nsw[i]] = i;
	}
	// cout << endl;
	int need = 0;
	for (int i=0; i<n; i++) {
		if (nsw[i] == i) continue;
		need++;
		int ati = nsw[i];
		int whei = where[i];
		where[ati] = whei;
		where[i] = i;
		nsw[i] = i;
		nsw[whei] = ati;
		ans.push_back(make_pair(i, whei));
	}
	// cout << "req: " << need << " have: " << sw << endl;
	// if (sw == 3) return true;
	return need <= sw;
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {

    n = N;
    m = M;
    for (int i=0; i<n; i++) seq[i] = S[i];
    for (int i=0; i<m; i++) {
		plan.push_back(make_pair(X[i], Y[i]));
	}
    
    for (int j=0; j<=M; j++) {
		if (works(j)) {
			for (int i=0; i<j; i++) {
				if (i < ans.size()) {
					P[i] = ans[i].first;
					Q[i] = ans[i].second;
				}
				else {
					P[i] = 0;
					Q[i] = 0;
				}
			}
			return j;
		}
	}
    
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:55:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (i < ans.size()) {
         ~~^~~~~~~~~~~~
sorting.cpp:68:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

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