Submission #992437

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Source Code Expand

#include <cstdio>
#include <cstring>
#include <cassert>
#include <cmath>
#include <vector>
#include <list>
#include <string>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <iostream>
#include <sstream>
using namespace std;

typedef long long i64;
const int inf = (int)1.05e9;


int main()
{
	int n;
	int m;
	vector<int> xs;
	vector<int> count;
	vector<int> same;

	scanf("%d%d", &n, &m);
	xs.resize(n);
	count.resize(m);
	same.resize(m);
	for(int i = 0; i < n; ++i) {
		int x;
		scanf("%d", &x);
		xs[i] = x;
	}

	sort(xs.begin(), xs.end());

	for(int i = 0; i < n; ++i)
		count[xs[i] % m] += 1;
	int lit = 0;
	while(lit < n) {
		int rit = lit + 1;
		while(xs[rit] == xs[lit] && rit < n)
			rit += 1;
		int c = (rit - lit) / 2;
		same[xs[lit] % m] += c;
		lit = rit;
	}

	int ans = 0;

	for(int i = 0; i <= (m - i); ++i) {

		int l = i;
		int r = (m - i);

		if(l == 0) {
			ans += count[l] / 2;
			continue;
		} else if(l == r) {
			ans += count[l] / 2;
			continue;
		}

		int pa = min(count[l], count[r]);

		int sa_l = min((count[l] - pa) / 2, same[l]);
		int sa_r = min((count[r] - pa) / 2, same[r]);

		//printf("%d: %d %d %d\n", i, pa, sa_l, sa_r);

		ans += (pa + sa_l + sa_r);
	}

	printf("%d\n", ans);

	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:29:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &m);
                       ^
./Main.cpp:35:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &x);
                  ^

Judge Result