Submission #1124048

#	Time	Username	Problem	Language	Result	Execution time	Memory
1124048		gdragon	Money (IZhO17_money)	C++20	45 / 100	7 ms	832 KiB

money

#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 1e5 + 5;
const int inf = 1e9 + 7;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
void add(int &x, int y) {x += y; if (x >= mod) x -= mod;}
void sub(int &x, int y) {x -= y; if (x < 0) x += mod;}
int mul(int x, int y) {return 1LL * x * y % mod;}
// -----------------------------------------//
int n;
int a[N];
void read() {
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> a[i];
}
void sub3() {
    vector<vector<bool>> dp;
    vector<int> val[305];
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= i; j++) val[i].push_back(a[j]);
        sort(ALL(val[i]));
        val[i].erase(unique(ALL(val[i])), val[i].end());
    }
    val[0].push_back(0);
    dp.assign(n + 2, vector<bool>(n + 2, 0));
    dp[0][0] = 1;
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= i; j++) {
            dp[i][j] = dp[i - 1][j - 1];
            for(int k = i; k >= 1 && !dp[i][j]; k--) {
                if (k < i && a[k] > a[k + 1]) break;
                if (!dp[k - 1][j - 1]) continue;
                if (a[i] <= val[k - 1][0]) {
                    dp[i][j] = 1;
                    // cout << i << ' ' << j << ' ' << k << ' ' << "FIRST\n";
                }
                else if (a[k] >= val[k - 1].back()) {
                    dp[i][j] = 1;
                    // cout << i << ' ' << j << ' ' << k << ' ' << "LAST\n";
                }
                else {
                    int p = upper_bound(ALL(val[k - 1]), a[k]) - val[k - 1].begin() - 1;
                    if (p < val[k - 1].size() && val[k - 1][p + 1] >= a[i]) dp[i][j] = 1;
                    // cout << i << ' ' << j << ' ' << k << ' ' << val[k - 1][p] << " MID\n";
                }
            }
        }
    }
    for(int i = 1; i <= n; i++) if (dp[n][i]) {
        cout << i;
        break;
    }
}
void solve() {
    // if (n <= 300) {
    //     sub3();
    //     return;
    // }
    set<int> s;
    int ans = 0;
    a[n + 1] = inf;
    for(int i = 1; i <= n; i++) {
        if (s.empty()) {
            int j = i + 1;
            s.insert(a[i]);
            while(j <= n && a[j] >= a[j - 1]) {
                s.insert(a[j]);
                ++j;
            }
            --j;
            i = j;
            ++ans;
            continue;
        }
        int firstVal = (*s.begin());
        int lastVal = (*s.rbegin());
        int rig = *s.upper_bound(a[i]);
        // cerr << i << ' ' << firstVal << ' ' << lastVal << endl;
        int j = i + 1;
        s.insert(a[i]);
        while(j <= n && a[j - 1] <= a[j]) {
            // cerr << i << ' ' << j << endl;
            if (a[i] >= lastVal) {
                s.insert(a[j]);
            }
            else if (a[i] < firstVal) {
                if (a[j] <= firstVal) s.insert(a[j]);
                else break;
            }
            else {
                if (a[j] <= rig) s.insert(a[j]);
                else break;
            }
            ++j;
        }
        //cerr << i << ' ' << j << endl;
        --j;
        i = j;
        ++ans;
    }
    cout << ans;
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    int test = 1;
    // cin >> test;
    while(test--) {
        read();
        solve();
    }
    return 0;
}

Compilation message (stderr)

money.cpp: In function 'int main()':
money.cpp:121:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  121 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
money.cpp:122:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  122 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 16 / 16
• Subtask 3: 20 / 20
• Subtask 4: 0 / 55