結果

問題 No.1334 Multiply or Add
ユーザー 👑 emthrmemthrm
提出日時 2021-01-08 22:39:16
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 27 ms / 2,000 ms
コード長 6,474 bytes
コンパイル時間 2,146 ms
コンパイル使用メモリ 204,832 KB
最終ジャッジ日時 2025-01-17 13:02:32
ジャッジサーバーID
(参考情報)
judge2 / judge4
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ファイルパターン 結果
other AC * 71
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ソースコード

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プレゼンテーションモードにする

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
IOSetup() {
std::cin.tie(nullptr);
std::ios_base::sync_with_stdio(false);
std::cout << fixed << setprecision(20);
}
} iosetup;
template <int MOD>
struct MInt {
unsigned val;
MInt(): val(0) {}
MInt(long long x) : val(x >= 0 ? x % MOD : x % MOD + MOD) {}
static int get_mod() { return MOD; }
static void set_mod(int divisor) { assert(divisor == MOD); }
MInt pow(long long exponent) const {
MInt tmp = *this, res = 1;
while (exponent > 0) {
if (exponent & 1) res *= tmp;
tmp *= tmp;
exponent >>= 1;
}
return res;
}
MInt &operator+=(const MInt &x) { if((val += x.val) >= MOD) val -= MOD; return *this; }
MInt &operator-=(const MInt &x) { if((val += MOD - x.val) >= MOD) val -= MOD; return *this; }
MInt &operator*=(const MInt &x) { val = static_cast<unsigned long long>(val) * x.val % MOD; return *this; }
MInt &operator/=(const MInt &x) {
// assert(std::__gcd(static_cast<int>(x.val), MOD) == 1);
unsigned a = x.val, b = MOD; int u = 1, v = 0;
while (b) {
unsigned tmp = a / b;
std::swap(a -= tmp * b, b);
std::swap(u -= tmp * v, v);
}
return *this *= u;
}
bool operator==(const MInt &x) const { return val == x.val; }
bool operator!=(const MInt &x) const { return val != x.val; }
bool operator<(const MInt &x) const { return val < x.val; }
bool operator<=(const MInt &x) const { return val <= x.val; }
bool operator>(const MInt &x) const { return val > x.val; }
bool operator>=(const MInt &x) const { return val >= x.val; }
MInt &operator++() { if (++val == MOD) val = 0; return *this; }
MInt operator++(int) { MInt res = *this; ++*this; return res; }
MInt &operator--() { val = (val == 0 ? MOD : val) - 1; return *this; }
MInt operator--(int) { MInt res = *this; --*this; return res; }
MInt operator+() const { return *this; }
MInt operator-() const { return MInt(val ? MOD - val : 0); }
MInt operator+(const MInt &x) const { return MInt(*this) += x; }
MInt operator-(const MInt &x) const { return MInt(*this) -= x; }
MInt operator*(const MInt &x) const { return MInt(*this) *= x; }
MInt operator/(const MInt &x) const { return MInt(*this) /= x; }
friend std::ostream &operator<<(std::ostream &os, const MInt &x) { return os << x.val; }
friend std::istream &operator>>(std::istream &is, MInt &x) { long long val; is >> val; x = MInt(val); return is; }
};
namespace std { template <int MOD> MInt<MOD> abs(const MInt<MOD> &x) { return x; } }
template <int MOD>
struct Combinatorics {
using ModInt = MInt<MOD>;
int val; // "val!" and "mod" must be disjoint.
std::vector<ModInt> fact, fact_inv, inv;
Combinatorics(int val = 10000000) : val(val), fact(val + 1), fact_inv(val + 1), inv(val + 1) {
fact[0] = 1;
for (int i = 1; i <= val; ++i) fact[i] = fact[i - 1] * i;
fact_inv[val] = ModInt(1) / fact[val];
for (int i = val; i > 0; --i) fact_inv[i - 1] = fact_inv[i] * i;
for (int i = 1; i <= val; ++i) inv[i] = fact[i - 1] * fact_inv[i];
}
ModInt nCk(int n, int k) const {
if (n < 0 || n < k || k < 0) return 0;
assert(n <= val && k <= val);
return fact[n] * fact_inv[k] * fact_inv[n - k];
}
ModInt nPk(int n, int k) const {
if (n < 0 || n < k || k < 0) return 0;
assert(n <= val);
return fact[n] * fact_inv[n - k];
}
ModInt nHk(int n, int k) const {
if (n < 0 || k < 0) return 0;
return k == 0 ? 1 : nCk(n + k - 1, k);
}
};
using ModInt = MInt<MOD>;
// https://codeforces.com/contest/1461/problem/F
ModInt solve(vector<int> a) {
int n = a.size();
if (n == 1) return a[0];
if (n == 2) return 1LL * a[0] * a[1];
vector<ll> mul(n);
mul[0] = a[0];
FOR(i, 1, n) mul[i] = min(mul[i - 1] * a[i], 1LL * INF);
if (mul[n - 1] == INF) {
ModInt res = 1;
for (int e : a) res *= e;
return res;
}
vector<int> b;
for (int i = 0; i < n;) {
int j = i + 1;
if (a[i] == 1) {
while (j < n && a[j] == 1) ++j;
b.emplace_back(j - i);
} else {
int mul = a[i];
while (j < n && a[j] > 1) mul *= a[j++];
b.emplace_back(mul);
}
i = j;
}
int m = b.size();
assert(m % 2 == 1);
vector<ll> dp(m, -LINF);
vector<int> prev(m, -1);
dp[0] = b[0];
prev[0] = 0;
for (int i = 2; i < m; i += 2) {
dp[i] = dp[i - 2] + b[i - 1] + b[i];
prev[i] = i;
int mul = b[i];
for (int j = i - 2; j >= 0; j -= 2) {
mul *= b[j];
if (dp[i] < (j == 0 ? 0 : dp[j - 2] + b[j - 1]) + mul) {
dp[i] = (j == 0 ? 0 : dp[j - 2] + b[j - 1]) + mul;
prev[i] = j;
}
}
}
int pos = m - 1;
vector<bool> plus(m, true);
while (pos >= 0) {
FOR(i, prev[pos], pos) plus[i] = false;
pos = prev[pos] - 2;
}
string ans = "";
bool ast = true;
for (int i = 0, idx = 0; i < n; ++idx) {
int j = i;
if (a[i] == 1) {
while (j < n && a[j] == 1) {
ans += ast ? '*' : '+';
++j;
}
} else {
while (j < n && a[j] > 1) {
ans += '*';
++j;
}
ans.pop_back();
ast = !plus[idx];
ans += ast ? '*' : '+';
}
i = j;
}
ans.pop_back();
ModInt res = 0, cur = a[0];
for (int i = 1; i < n; ++i) {
if (ans[i - 1] == '+') {
res += cur;
cur = a[i];
} else if (ans[i - 1] == '*') {
cur *= a[i];
}
}
return res + cur;
}
int main() {
int n; cin >> n;
vector<int> a(n); REP(i, n) cin >> a[i];
ModInt ans = 0;
for (int i = 0; i < n;) {
if (a[i] == 1) {
ans += a[i++];
continue;
}
int j = n - 1;
while (j >= i && a[j] == 1) --j;
ans += solve(vector<int>(a.begin() + i, a.begin() + j + 1));
ans += n - (j + 1);
break;
}
cout << ans << '\n';
return 0;
}
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