Submission #516349

#	Time	Username	Problem	Language	Result	Execution time	Memory
516349		qwerasdfzxcl	Monochrome Points (JOI20_monochrome)	C++14	25 / 100	2065 ms	320 KiB

monochrome

#include <bits/stdc++.h>

typedef long long ll;
using namespace std;
const ll INF = 1e18;
char a[400400];
int B[200200], W[200200];
vector<pair<int, int>> E;

int calc(){
    for (auto &p:E) if (p.first > p.second) swap(p.first, p.second);
    sort(E.begin(), E.end());

    int ret = 0;
    for (int i=0;i<(int)E.size();i++){
        //printf("%d %d\n", E[i].first, E[i].second);
        for (int j=i+1;j<(int)E.size();j++) if (E[j].first < E[i].second && E[i].second < E[j].second) ret++;
    }
    //printf("\n");
    return ret;
}

int main(){
    int n;
    scanf("%d", &n);
    scanf("%s", a+1);
    n *= 2;

    int cb = 0, cw = 0;
    for (int i=1;i<=n;i++){
        if (a[i]=='B') B[++cb] = i;
        else W[++cw] = i;
    }

    int ans = 0;
    for (int z=1;z<=n/2;z++){
        E.clear();
        int pt = z;
        for (int i=1;i<=n/2;i++){
            E.emplace_back(B[i], W[pt]);
            pt++;
            if (pt>n/2) pt -= n/2;
        }

        ans = max(ans, calc());
    }
    printf("%d\n", ans);
    return 0;
}

Compilation message (stderr)

monochrome.cpp: In function 'int main()':
monochrome.cpp:25:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
monochrome.cpp:26:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |     scanf("%s", a+1);
      |     ~~~~~^~~~~~~~~~~

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