diff --git "a/khj20006/202512/22 BOJ P3 \354\210\230\354\227\264\354\235\230 \352\260\234\354\210\230 NKD.md" "b/khj20006/202512/22 BOJ P3 \354\210\230\354\227\264\354\235\230 \352\260\234\354\210\230 NKD.md" new file mode 100644 index 00000000..1311e915 --- /dev/null +++ "b/khj20006/202512/22 BOJ P3 \354\210\230\354\227\264\354\235\230 \352\260\234\354\210\230 NKD.md" @@ -0,0 +1,77 @@ +```java +import java.util.*; +import java.io.*; + +public class Main { + + static BufferedReader br; + static BufferedWriter bw; + static StringTokenizer st; + + static final long MOD = (long)1e9 + 7; + static int N, K, D; + static long[] dp; + + public static void main(String[] args) throws Exception { + bw = new BufferedWriter(new OutputStreamWriter(System.out)); + + input(); + solve(); + + bw.close(); + } + + public static void input() throws Exception { + br = new BufferedReader(new InputStreamReader(System.in)); + + st = new StringTokenizer(br.readLine()); + N = Integer.parseInt(st.nextToken()); + K = Integer.parseInt(st.nextToken()); + D = Integer.parseInt(st.nextToken()); + + br.close(); + } + + public static void solve() throws Exception { + bw = new BufferedWriter(new OutputStreamWriter(System.out)); + + if(K > 446) { + bw.write("0"); + return; + } + if(K == 1) { + bw.write(N <= D ? "1" : "0"); + return; + } + + dp = new long[N+2]; + for(int k=1;k<=K;k++) { + long[] pre = new long[N+2]; + if(k == 1) { + for(int i=1;i<=D;i++) { + if(2*i+1 <= N) pre[2*i+1] = (pre[2*i+1] + 1) % MOD; + if(2*i+D+1 <= N) pre[2*i+D+1] = (pre[2*i+D+1] + MOD - 1) % MOD; + } + } + else { + int limit = (long)k * D >= (long)N ? N : k * D; + for(int i=1;i<=limit;i++) { + if(2*limit+1 <= N) pre[2*limit+1] = (pre[2*limit+1] + dp[i]) % MOD; + if(2*limit+D+1 <= N) pre[2*limit+D+1] = (pre[2*limit+D+1] + MOD - dp[i]) % MOD; + } + } + + long s = 0; + for(int i=1;i<=N;i++) { + s = (s + pre[i]) % MOD; + pre[i] = s; + } + for(int i=1;i<=N;i++) dp[i] = pre[i]; + } + bw.write(dp[N] + "\n"); + + bw.close(); + } + +} +```