Submission #209868

#	Time	Username	Problem	Language	Result	Execution time	Memory
209868		bash	Tents (JOI18_tents)	C++17	100 / 100	236 ms	87460 KiB

tents

/**
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*/
#include <cstring>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <queue>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cassert>
 
#define F first
#define S second
#define endl '\n'
#define deb(x) cout<<#x<<' '<<x<<endl;
#define pb push_back
 using namespace __gnu_pbds;
using namespace std;

typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
/*
#ifdef IZI_KATKA
#define int __int64_t
#else
#define int __int64
#endif
*/
const long long MOD = 1e9 + 7;
const long long MAXN = 1e6 + 1;

typedef long long ll;

#define pii pair<int,int>
 
long long readInt() {
    bool minus1 = false;
    long long result = 0;
    char ch;
    ch = getchar();
    while (true) {
        if (ch == '-') break;
        if (ch >= '0' && ch <= '9') break;
        ch = getchar();
    }
    if (ch == '-') minus1 = true; else result = ch-'0';
    while (true) {
        ch = getchar();
        if (ch < '0' || ch > '9') break;
        result = result*10 + (ch - '0');
    }
    if (minus1)
        return -result;
    else
        return result;
}

#define int ll

const int N = 3333;

int dp[N][N];
int solve(int n, int m) {
	if (~dp[n][m]) return dp[n][m];
	if (n == 0 || m == 0) {
		return dp[n][m] = 1;
	}
	int &ans = dp[n][m];
	ans = 0;
	ans += solve(n - 1, m);
	ans += 4 * m * solve(n - 1, m - 1);
	if (m >= 2)
		ans += (m * (m - 1) / 2) * solve(n - 1, m - 2);
	if (n >= 2)
		ans +=  m * (n - 1) * solve(n - 2, m - 1);
	ans %= MOD;	
	return ans;
}
main() {
	#ifdef IZI_KATKA
	assert(freopen("input", "r", stdin));
    assert(freopen("output", "w", stdout));
    #endif
    int n = readInt(), m = readInt();
    memset(dp, -1, sizeof(dp));
    cout << (solve(n, m) + MOD - 1) % MOD;
	return 0;
}

Compilation message (stderr)

tents.cpp:100:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main() {
      ^

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52