Submission #992126

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Source Code Expand

#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

#define rep(i, N) for (int i = 0; i < N; i++)
#define pb push_back

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	int N, M; cin >> N >> M;
	vector<int> a(N);
	rep(i, N) scanf("%d", &a[i]);
	vector<int> b(100001);
	rep(i, N) b[a[i]]++;
	vector<int> c(M), d(M);
	rep(x, 100001) {
		c[x % M] += b[x];
		d[x % M] += b[x] / 2;
	}
	int ans = 0;
	for (int x = 0; x * 2 <= M; x++) {
		if (x == 0 || x * 2 == M) {
			ans += c[x] / 2;
			continue;
		}
		int y = M - x;
		if (c[x] > c[y]) {
			swap(c[x], c[y]);
			swap(d[x], d[y]);
		}
		ans += c[x] + min(d[y], (c[y] - c[x]) / 2);
	}
	cout << ans << endl;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:39:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  rep(i, N) scanf("%d", &a[i]);
                              ^

Judge Result