Submission #1282649

#	Time	Username	Problem	Language	Result	Execution time	Memory
1282649		khanhgng	Monochrome Points (JOI20_monochrome)	C++20	0 / 100	1 ms	576 KiB

monochrome

//#pragma GCC target("avx2")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
#define ll long long
#define int long long
#define ld long double
#define pb push_back
#define pii pair<int, int>
#define fi first
#define se second
#define bit(i, x) ((x >> i) & 1)
#define SZ(x) ((int)(x.size()))
#define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for (int i = (a); i >= (b); --i)
#define task "test"

using namespace std;

mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
ll Rand(ll l, ll r) { assert(l <= r); return uniform_int_distribution<ll>(l, r)(rd); }

const int MAXn = 5e5+10;
const int MAX = 1e5+10;
const ll INF = (long long)(1e18);
const ll INF1 = (long long)(1e17);
const int MOD = 1e9 + 7;
const int MOD1 = 111539786;
const int BASE = 3137;
const int BL = 340;

int n,b[MAXn];
char a[MAXn];
vector<int>vec[2];

struct BIT{
    int N,f[MAXn*4];
    void init(int n){
        N=n;
        FOR(i,1,n)f[i]=0;
    }
    void upd(int idx){
        for(int i=idx;i<=N;i+=(i&-i))++f[i];
    }
    int get(int idx){
        int res=0;
        for(int i=idx;i>0;i-=(i&-i))res+=f[i];
        return res;
    }
}st;

void solution() {
    cin>>n;
    FOR(i,1,n)cin>>a[i];
    FOR(i,n+1,2*n){
        cin>>a[i];
        if(a[i]=='W'){
            vec[0].pb(i);
        }
        else {
            vec[1].pb(i);
        }
    }
    int u=0,v=0;
    FOR(i,1,n){
        if(a[i]=='W'){
            b[i]=vec[1][v];
            ++v;
        }
        else {
            b[i]=vec[0][u];
            ++u;
        }
    }
    st.init(2*n+5);
    int res=0;
    FORD(i,n,1){
        res+=st.get(2*n+1)-st.get(b[i]);
        st.upd(b[i]);
    }
    cout<<res;
}

int32_t main() {
    if (fopen(task".inp", "r")){freopen(task".inp", "r", stdin);freopen(task".out", "w", stdout);}
    ios::sync_with_stdio(0); cin.tie(0);
    int ntest = 1;///cin >> ntest;
    while (ntest--) solution();
    cerr << "\n" << 1.0 * clock() / CLOCKS_PER_SEC << "s ";
}

Compilation message (stderr)

monochrome.cpp: In function 'int32_t main()':
monochrome.cpp:85:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   85 |     if (fopen(task".inp", "r")){freopen(task".inp", "r", stdin);freopen(task".out", "w", stdout);}
      |                                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
monochrome.cpp:85:72: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   85 |     if (fopen(task".inp", "r")){freopen(task".inp", "r", stdin);freopen(task".out", "w", stdout);}
      |                                                                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 4
• Subtask 2: 0 / 21
• Subtask 3: 0 / 10
• Subtask 4: 0 / 65