added solution to codeforces problem 1110D

codeforces/D/1110D.cpp

@@ -0,0 +1,80 @@
+// https://codeforces.com/contest/1110/problem/D
+#include <iostream>
+#include <vector>
+#include <queue>
+#include <stack>
+#include <algorithm>
+#include <math.h>
+#include <string>
+#include <cstring>
+#include <set>
+#include <map>
+#include <unordered_map>
+#include <assert.h>
+#include <array>
+#include <random>
+#include <chrono>
+
+using namespace std;
+
+typedef long long ll;
+typedef long double ld;
+typedef pair<int, int> pii;
+typedef pair<int, pair<int, int>> piii;
+typedef vector<int> vi;
+typedef vector<pii> vii;
+
+int dadsadasda;
+
+#define ri(a) dadsadasda=scanf("%d", &a)
+#define rii(a,b) dadsadasda=scanf("%d %d", &a, &b)
+#define riii(a,b,c) dadsadasda=scanf("%d %d %d", &a, &b, &c)
+#define rl(a) dadsadasda=scanf("%lld", &a)
+#define rll(a,b) dadsadasda=scanf("%lld %lld", &a, &b)
+#define FOR(i,n,m) for(int i=n; i<m; i++)
+#define ROF(i,n,m) for(int i=n; i>m; i--)
+#define pb push_back
+#define lb lower_bound
+#define ub upper_bound
+#define F first
+#define S second
+#define ALL(s) s.begin(),s.end()
+#define SZ(s) (int)s.size()
+
+const int INF = 0x3f3f3f3f;
+const ll LLINF = 1e18;
+const int MAXN = 1e6 + 30; // CAMBIAR ESTE
+//mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
+
+// GJNM
+int N, M;
+int CNT[MAXN];
+
+int DP[MAXN][3][3];
+int f(int p, int t1, int t2) {
+    if (p == MAXN - 10)
+        return 0;
+    int &ret = DP[p][t1][t2];
+    if (ret != -1)
+        return ret;
+    ret = -INF;
+    FOR(t3, 0, 3) {
+        int a = t1, b = t1 + t2, c = t1 + t2 + t3, d = t2 + t3, e = t3;
+        if (a > CNT[p - 1] || b > CNT[p] || c > CNT[p + 1] || d > CNT[p + 2] || e > CNT[p + 3])
+            continue;
+        ret = max(ret, t1 + (CNT[p + 1] - c) / 3 + f(p + 1, t2, t3));
+    }
+    return ret;
+}
+
+int main() {
+    memset(DP, -1, sizeof(DP));
+    rii(N, M);
+    FOR(i, 0, N) {
+        int a; ri(a);
+        CNT[a + 6]++;
+    }
+    int ans = 0;
+    printf("%d\n", ans + f(1, 0, 0));
+    return 0;
+}