結果
| 問題 |
No.978 Fibonacci Convolution Easy
|
| ユーザー |
 Oland
|
| 提出日時 | 2020-02-01 07:24:34 |
| 言語 | Java (openjdk 23) |
| 結果 |
AC
|
| 実行時間 | 201 ms / 2,000 ms |
| コード長 | 7,323 bytes |
| コンパイル時間 | 2,466 ms |
| コンパイル使用メモリ | 78,460 KB |
| 実行使用メモリ | 38,636 KB |
| 最終ジャッジ日時 | 2024-09-18 21:04:58 |
| 合計ジャッジ時間 | 5,981 ms |
|
ジャッジサーバーID （参考情報） |
judge2 / judge5 |
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| ファイルパターン | 結果 |
|---|---|
| other | AC * 21 |
ソースコード
import java.util.*;
import java.io.*;
@SuppressWarnings("unused")
public class Main {
FastScanner in;
PrintWriter out;
int MOD = (int)1e9+7;
long ceil(long a, long b){return (a + b - 1) / b;}
long gcd(long a, long b){return b == 0 ? a : gcd(b, a % b);}
long lcm(long a, long b){return a / gcd(a, b) * b;}
void solve(){
int N = in.nextInt(), p = in.nextInt();
if(N == 1){
out.println("0");
return;
}
long sum = 1, sum2 = 1;
long[] a = new long[]{0, 1, 0};
for(int i = 2; i < N; i++){
a[i % 3] = (p * a[(i + 2) % 3] % MOD + a[(i + 1) % 3]) % MOD;
sum = (sum + a[i % 3]) % MOD;
sum2 = (sum2 + a[i % 3] * a[i % 3] % MOD) % MOD;
}
long ans = (sum * sum % MOD + sum2) % MOD * modMultiInv(2, MOD) % MOD;
out.println(ans);
}
//n^-1 % MOD をlog(MOD)で計算
public static long modMultiInv(long a, int mod){
return modPow(a, mod-2, mod);
}
//a^b % MOD をlog(b)で計算
public static long modPow(long a, long b, int mod){
long res = 1;
while(b > 0){
if((b & 1) == 1) res = (res * a) % mod;
a = (a * a) % mod;
b = b >> 1;
}
return res;
}
public static void main(String[] args) {
new Main().m();
}
private void m() {
in = new FastScanner(System.in);
out = new PrintWriter(System.out);
/*
try {
String path = "input.txt";
out = new PrintWriter(new BufferedWriter(new FileWriter(new File(path))));
}catch (IOException e){
e.printStackTrace();
}
*/
solve();
out.flush();
in.close();
out.close();
}
static class FastScanner {
private Reader input;
public FastScanner() {this(System.in);}
public FastScanner(InputStream stream) {this.input = new BufferedReader(new InputStreamReader(stream));}
public void close() {
try {
this.input.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public int nextInt() {return (int) nextLong();}
public long nextLong() {
try {
int sign = 1;
int b = input.read();
while ((b < '0' || '9' < b) && b != '-' && b != '+') {
b = input.read();
}
if (b == '-') {
sign = -1;
b = input.read();
} else if (b == '+') {
b = input.read();
}
long ret = b - '0';
while (true) {
b = input.read();
if (b < '0' || '9' < b) return ret * sign;
ret *= 10;
ret += b - '0';
}
} catch (IOException e) {
e.printStackTrace();
return -1;
}
}
public double nextDouble() {
try {
double sign = 1;
int b = input.read();
while ((b < '0' || '9' < b) && b != '-' && b != '+') {
b = input.read();
}
if (b == '-') {
sign = -1;
b = input.read();
} else if (b == '+') {
b = input.read();
}
double ret = b - '0';
while (true) {
b = input.read();
if (b < '0' || '9' < b) break;
ret *= 10;
ret += b - '0';
}
if (b != '.') return sign * ret;
double div = 1;
b = input.read();
while ('0' <= b && b <= '9') {
ret *= 10;
ret += b - '0';
div *= 10;
b = input.read();
}
return sign * ret / div;
} catch (IOException e) {
e.printStackTrace();
return Double.NaN;
}
}
public char nextChar() {
try {
int b = input.read();
while (Character.isWhitespace(b)) {
b = input.read();
}
return (char) b;
} catch (IOException e) {
e.printStackTrace();
return 0;
}
}
public String nextStr() {
try {
StringBuilder sb = new StringBuilder();
int b = input.read();
while (Character.isWhitespace(b)) {
b = input.read();
}
while (b != -1 && !Character.isWhitespace(b)) {
sb.append((char) b);
b = input.read();
}
return sb.toString();
} catch (IOException e) {
e.printStackTrace();
return "";
}
}
public String nextLine() {
try {
StringBuilder sb = new StringBuilder();
int b = input.read();
while (b != -1 && b != '\n') {
sb.append((char) b);
b = input.read();
}
return sb.toString();
} catch (IOException e) {
e.printStackTrace();
return "";
}
}
public int[] nextIntArray(int n) {
int[] res = new int[n];
for (int i = 0; i < n; i++) {
res[i] = nextInt();
}
return res;
}
public int[] nextIntArrayDec(int n) {
int[] res = new int[n];
for (int i = 0; i < n; i++) {
res[i] = nextInt() - 1;
}
return res;
}
public int[] nextIntArray1Index(int n) {
int[] res = new int[n + 1];
for (int i = 0; i < n; i++) {
res[i + 1] = nextInt();
}
return res;
}
public long[] nextLongArray(int n) {
long[] res = new long[n];
for (int i = 0; i < n; i++) {
res[i] = nextLong();
}
return res;
}
public long[] nextLongArrayDec(int n) {
long[] res = new long[n];
for (int i = 0; i < n; i++) {
res[i] = nextLong() - 1;
}
return res;
}
public long[] nextLongArray1Index(int n) {
long[] res = new long[n + 1];
for (int i = 0; i < n; i++) {
res[i + 1] = nextLong();
}
return res;
}
public double[] nextDoubleArray(int n) {
double[] res = new double[n];
for (int i = 0; i < n; i++) {
res[i] = nextDouble();
}
return res;
}
}
}