Submission #1356129


Source Code Expand

// Copyright (C) 2017 __debug.

// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; version 3

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; If not, see <http://www.gnu.org/licenses/>.


#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/priority_queue.hpp>

#define x first
#define y second
#define MP std::make_pair
#define SZ(x) ((int)(x).size())
#define ALL(x) (x).begin(), (x).end()
#define DEBUG(...) fprintf(stderr, __VA_ARGS__)
#ifdef __linux__
#define getchar getchar_unlocked
#define putchar putchar_unlocked
#endif

using std::pair;
using std::vector;
using std::string;

typedef long long LL;
typedef pair<int, int> Pii;

const int oo = 0x3f3f3f3f;

template<typename T> inline bool chkmax(T &a, T b) { return a < b ? a = b, true : false; }
template<typename T> inline bool chkmin(T &a, T b) { return b < a ? a = b, true : false; }
string procStatus()
{
    std::ifstream t("/proc/self/status");
    return string(std::istreambuf_iterator<char>(t), std::istreambuf_iterator<char>());
}
template<typename T> T read(T &x)
{
    int f = 1;
    char ch = getchar();
    for (; !isdigit(ch); ch = getchar())
        f = (ch == '-' ? -1 : 1);
    for (x = 0; isdigit(ch); ch = getchar())
        x = 10 * x + ch - '0';
    return x *= f;
}
template<typename T> void write(T x)
{
    if (x == 0) {
        putchar('0');
        return;
    }
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    static char s[20];
    int top = 0;
    for (; x; x /= 10)
        s[++top] = x % 10 + '0';
    while (top)
        putchar(s[top--]);
}
// EOT

const int MAXN = 3e3 + 5;
const int MOD = 1e9 + 7;

int N, M;

void solve()
{
    static int dp[MAXN][MAXN][2];

    dp[0][0][1] = 1;
    for (int i = 1; i <= N; ++i) {
        dp[0][i][0] = 1;
    }
    for (int i = 0; i < M; ++i) {
        for (int j = 0; j <= N; ++j) {
            for (int k = 0; k <= 1; ++k) {
                if (j) (dp[i + 1][j][k | (j - 1 == 0)] += dp[i][j][k]) %= MOD;
                if (j) (dp[i + 1][j - 1][k | (j - 1 == 0)] += dp[i][j][k]) %= MOD;
                if (N - j) (dp[i + 1][j][k] += dp[i][j][k]) %= MOD;
                if (N - j) (dp[i + 1][j + 1][k] += dp[i][j][k]) %= MOD;
            }
        }
    }
    int ans = 0;
    for (int i = 0; i <= N; ++i) {
        (ans += dp[M][i][1]) %= MOD;
    }

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

int main()
{
#ifdef __DEBUG
    freopen("D.in", "r", stdin);
    freopen("D.out", "w", stdout);
#endif

    read(N); read(M);
    solve();

    return 0;
}

// 万壑树参天,千山响杜鹃。
//     -- 王维《送梓州李使君》

Submission Info

Submission Time
Task D - Piling Up
User Ivlleiooq
Language C++14 (GCC 5.4.1)
Score 900
Code Size 3146 Byte
Status AC
Exec Time 194 ms
Memory 70656 KB

Judge Result

Set Name Sample All
Score / Max Score 0 / 0 900 / 900
Status
AC × 3
AC × 33
Set Name Test Cases
Sample sample_01.txt, sample_02.txt, sample_03.txt
All sample_01.txt, sample_02.txt, sample_03.txt, sample_01.txt, sample_02.txt, sample_03.txt, subtask_1_01.txt, subtask_1_02.txt, subtask_1_03.txt, subtask_1_04.txt, subtask_1_05.txt, subtask_1_06.txt, subtask_1_07.txt, subtask_1_08.txt, subtask_1_09.txt, subtask_1_10.txt, subtask_1_11.txt, subtask_1_12.txt, subtask_1_13.txt, subtask_1_14.txt, subtask_1_15.txt, subtask_1_16.txt, subtask_1_17.txt, subtask_1_18.txt, subtask_1_19.txt, subtask_1_20.txt, subtask_1_21.txt, subtask_1_22.txt, subtask_1_23.txt, subtask_1_24.txt, subtask_1_25.txt, subtask_1_26.txt, subtask_1_27.txt
Case Name Status Exec Time Memory
sample_01.txt AC 1 ms 256 KB
sample_02.txt AC 1 ms 384 KB
sample_03.txt AC 75 ms 69248 KB
subtask_1_01.txt AC 33 ms 14592 KB
subtask_1_02.txt AC 17 ms 27520 KB
subtask_1_03.txt AC 61 ms 68992 KB
subtask_1_04.txt AC 56 ms 38400 KB
subtask_1_05.txt AC 140 ms 61696 KB
subtask_1_06.txt AC 61 ms 68992 KB
subtask_1_07.txt AC 68 ms 64768 KB
subtask_1_08.txt AC 26 ms 45952 KB
subtask_1_09.txt AC 131 ms 70144 KB
subtask_1_10.txt AC 194 ms 70656 KB
subtask_1_11.txt AC 61 ms 64640 KB
subtask_1_12.txt AC 41 ms 40064 KB
subtask_1_13.txt AC 55 ms 68992 KB
subtask_1_14.txt AC 30 ms 60160 KB
subtask_1_15.txt AC 21 ms 21632 KB
subtask_1_16.txt AC 71 ms 69248 KB
subtask_1_17.txt AC 25 ms 33792 KB
subtask_1_18.txt AC 32 ms 29952 KB
subtask_1_19.txt AC 36 ms 68608 KB
subtask_1_20.txt AC 75 ms 69248 KB
subtask_1_21.txt AC 6 ms 27264 KB
subtask_1_22.txt AC 14 ms 68352 KB
subtask_1_23.txt AC 8 ms 35456 KB
subtask_1_24.txt AC 15 ms 68352 KB
subtask_1_25.txt AC 1 ms 384 KB
subtask_1_26.txt AC 15 ms 68352 KB
subtask_1_27.txt AC 1 ms 256 KB