제출 #961274

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
961274		BhavayGoyal	Group Photo (JOI21_ho_t3)	C++14	100 / 100	376 ms	600 KiB

Main

#include <bits/stdc++.h>
using namespace std;

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<class T> using oset = 
            tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define ll long long
#define ld long double
#define ar array
#define vi vector<int>
#define vii vector<vector<int>>
#define pii pair<int, int>
#define pb push_back
#define all(x) x.begin(), x.end()
#define f first
#define s second
#define endl "\n"

const int MOD = 1e9+7;
const int inf = 1e9;
const ll linf = 1e18;

const int d4i[4]={-1, 0, 1, 0}, d4j[4]={0, 1, 0, -1};
const int d8i[8]={-1, -1, 0, 1, 1, 1, 0, -1}, d8j[8]={0, 1, 1, 1, 0, -1, -1, -1};

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());


// -------------------------------------------------- Main Code --------------------------------------------------

struct bits {
    int n; 
    vi tree;

    bits(int N) {n = N+5; tree = vi(n+5);}

    void update(int idx, int val) { for (idx; idx <= n; idx += (idx&-idx)) tree[idx] += val; }
    int sum(int idx) { int ans = 0; for (idx; idx; idx -= (idx&-idx)) ans += tree[idx]; return ans; }
    int query(int l, int r) { return sum(r)-sum(l-1); }
};

const int N = 5001;
int a[N], pos[N], dp[N];

void sol() {
    int n; cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i], pos[a[i]] = i;

    for (int i = 1; i <= n; i++) dp[i] = inf;

    bits smaller(n+1);
    vi small(n+1);
    for (int i = 1; i <= n; i++) {
        smaller.update(pos[i], 1);
        int cost = 0;
        bits bigger(n);
        for (int j = i; j >= 1; j--) {
            // cost = (elements < j after pos[j]) + (elements > j && <= i after pos[j])
            if (i == j) small[i] = smaller.query(pos[j]+1, n);
            cost += small[j];
            cost += bigger.query(pos[j]+1, n);
            cost -= bigger.query(1, pos[j]-1);
            dp[i] = min(dp[j-1]+cost, dp[i]);
            bigger.update(pos[j], 1);
        }
    }
    cout << dp[n] << endl;
}

int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int t = 1;
    // cin >> t; 
    while (t--) {
        sol();
    }
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

Main.cpp: In member function 'void bits::update(int, int)':
Main.cpp:41:42: warning: statement has no effect [-Wunused-value]
   41 |     void update(int idx, int val) { for (idx; idx <= n; idx += (idx&-idx)) tree[idx] += val; }
      |                                          ^~~
Main.cpp: In member function 'int bits::sum(int)':
Main.cpp:42:42: warning: statement has no effect [-Wunused-value]
   42 |     int sum(int idx) { int ans = 0; for (idx; idx; idx -= (idx&-idx)) ans += tree[idx]; return ans; }
      |                                          ^~~

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 20 / 20
• Subtask 5: 36 / 36