Submission #114695

#	Time	Username	Problem	Language	Result	Execution time	Memory
114695		arman_ferdous	Sorting (IOI15_sorting)	C++17	20 / 100	36 ms	640 KiB

sorting

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

const int N = 2e5+100;
int n, ss[N], m, x[N], y[N], p[N], q[N];

int tmp[N];
int solve(int M) {
	for(int i = 0; i < n; i++)
		tmp[i] = ss[i];

	for(int i = 0; i < M; i++)
		swap(tmp[x[i]], tmp[y[i]]);
	int cur = 0, R = 0;
	for(int i = 0; i < n; ) {
		if(tmp[i] == i) { i++; continue; }
		int pp = i, qq = tmp[i];
		if(cur >= M) return -1;

		for(int j = M-1; j > cur; j--) {
			if((x[j] == pp && y[j] == qq) || (x[j] == qq && y[j] == pp)) swap(pp, qq);
    		else {
	    		if(x[j] == pp) pp = y[j];
	    		else if(y[j] == pp) pp = x[j];
	    		if(x[j] == qq) qq = y[j];
	    		else if(y[j] == qq) qq = x[j];
	    	}
		}

		p[R] = pp, q[R] = qq;
		R++, cur++;
		swap(tmp[i], tmp[tmp[i]]);
	}
	return R;
}

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++)
		ss[i] = S[i];
	for(int i = 0; i < m; i++)
		x[i] = X[i], y[i] = Y[i];

	int lo = 0, hi = M, idx;
	while(lo <= hi) {
		int mid = (lo + hi) >> 1;
		int R = solve(mid);
		if(R == -1) lo = mid+1;
		else idx = mid, hi = mid-1;
	}

	int R = solve(idx);
	for(int i = 0; i < R; i++)
		P[i] = p[i], Q[i] = q[i];
	return R;
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:53:19: warning: 'idx' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int R = solve(idx);
                   ^

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