Submission #991983

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Source Code Expand

#include <cstdio>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstring>
#include <string>
#include <cmath>
#include <cstdlib>
#include <iostream>

using namespace std;

#define MOD @
#define ADD(X,Y) ((X) = ((X) + (Y)) % MOD)
typedef long long i64; typedef vector<int> ivec; typedef vector<string> svec;

int N, M, X[101010];
vector<int> S[101010];

pair<int, int> trans(vector<int> &V)
{
	sort(V.begin(), V.end());

	int evepair = 0, odds = 0;

	int con = 0;
	for (int i = 0; i < V.size(); ++i) {
		++con;
		if (i == V.size() - 1 || V[i] != V[i + 1]) {
			evepair += con / 2;
			odds += con % 2;
			con = 0;
		}
	}
	return{ evepair, odds };
}

int solve(vector<int> &A, vector<int> &B)
{
	auto p = trans(A);
	auto q = trans(B);

	int ret = 0;
	ret += min(p.second, q.second);
	p.second -= ret;
	q.second -= ret;
	if (p.second == 0) swap(p, q);

	int oddp = min(p.second, q.first * 2);
	return ret + oddp + p.first + (q.first * 2 - oddp) / 2;
}

int main()
{
	scanf("%d%d", &N, &M);
	for (int i = 0; i < N; ++i) {
		scanf("%d", X + i);

		S[X[i] % M].push_back(X[i]);
	}

	int ret = 0;
	for (int i = 0; i < M; ++i) {
		int comp = (M - i) % M;
		if (i <= comp) {
			if (i == comp) ret += S[i].size() / 2;
			else ret += solve(S[i], S[comp]);
		}
	}
	printf("%d\n", ret);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:58:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &M);
                       ^
./Main.cpp:60:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", X + i);
                     ^

Judge Result