Submission #844838

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <ctype.h>
#include <deque>
#include <queue>
#include <cstring>
#include <set>
#include <list>
#include <map>
#include <random>
#include <unordered_map>
#include <stdio.h>

using namespace std;

typedef long long ll;
typedef std::vector<int> vi;
typedef std::vector<bool> vb;
typedef std::vector<string> vs;
typedef std::vector<double> vd;
typedef std::vector<long long> vll;
typedef std::vector<std::vector<int> > vvi;
typedef vector<vvi> vvvi;
typedef vector<vll> vvll;
typedef std::vector<std::pair<int, int> > vpi;
typedef vector<vpi> vvpi;
typedef std::pair<int, int> pi;
typedef std::pair<ll, ll> pll;
typedef std::vector<pll> vpll;

const long long mod = 1000000007;

#define all(c) (c).begin(),(c).end()
#define sz(c) (int)(c).size()
#define forn(i, a, b) for(int i = a; i < b; i++)

#define pb push_back
#define mp make_pair

int main()
{
#ifndef ONLINE_JUDGE
    freopen("input.txt", "rt", stdin);
    freopen("output.txt", "wt", stdout);
#endif
    int n;
    cin>>n;
    vi a(n);
    vpi b;
    forn(i,0,n) {
        cin>>a[i];
        b.pb(mp(a[i], i));
    }
    sort(all(b));
    int ans = 0;
    for(int i=0; i<n; i+=2) {
        if(i%2 != b[i].second % 2) ans++;
    }
    cout<<ans<<endl;
    
    
    
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:45:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     freopen("input.txt", "rt", stdin);
                                      ^
./Main.cpp:46:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
     freopen("output.txt", "wt", stdout);
                                        ^

Judge Result