Submission #992313

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Source Code Expand

#include <cstdio>
#include <cassert>
#include <set>
#include <map>
#include <vector>
using namespace std;

map<int, map<int, int>> byrem;

const int N = 100500;
bool was[N];

int sum(map<int, int> M) {
    int s = 0;
    for (auto pr : M)
        s += pr.second;
    return s;
}

int main() {
    int n, m;
    scanf("%d %d", &n, &m);
    for (int i = 0; i < n; i++) {
        int x;
        scanf("%d", &x);
        byrem[x % m][x]++;
    }
    int ans = 0;
    for (int a = 0; a < m; a++) {
        int b = (m - a) % m;
        if (was[a] || was[b])
            continue;
        was[a] = was[b] = true;
        if (a != b) {
            auto A = byrem[a];
            auto B = byrem[b];
            set<int> eA, oA;
            set<int> eB, oB;
            for (auto pr : A) {
                ((pr.second % 2) ? oA : eA).insert(pr.first);
            }
            for (auto pr : B) {
                ((pr.second % 2) ? oB : eB).insert(pr.first);
            }
            while (oA.size() > 0 && oB.size() > 0) {
                int x = *oA.begin();
                int y = *oB.begin();
                assert(A.count(x));
                assert(B.count(y));
                A[x]--;
                B[y]--;
                oA.erase(oA.begin());
                oB.erase(oB.begin());
                eA.insert(x);
                eB.insert(y);
                ans++;
            }
            if (!oB.empty()) {
                A.swap(B);
                oA.swap(oB);
                eA.swap(eB);
            }
            int sB = sum(B);
            int sA = sum(A);
            if ((int)oA.size() <= sB) {
                ans += (sA + sB) / 2;
            } else {
                ans += (sA + sB - (oA.size() - sB)) / 2;
            }
        } else {
            int s = sum(byrem[a]);
            ans += s / 2;
        }
    }
    printf("%d\n", ans);

}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:22:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &m);
                           ^
./Main.cpp:25:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &x);
                        ^

Judge Result