Submission #1101837

#	Time	Username	Problem	Language	Result	Execution time	Memory
1101837		blackslex	Global Warming (NOI13_gw)	C++17	0 / 40	595 ms	65536 KiB

gw

#include<bits/stdc++.h>

using namespace std;
using pii = pair<int, int>;

int n;

int main() {
    scanf("%d", &n);
    vector<int> a(n), par(n); iota(par.begin(), par.end(), 0);
    vector<bool> ck(n);
    for (auto &e: a) scanf("%d", &e);
    int cnt = 0, ans = 0;
    function<int(int)> fset = [&] (int x) {return (par[x] == x ? x : par[x] = fset(par[x]));};
    auto mg = [&] (int x, int y) {
        if ((x = fset(x)) == (y = fset(y))) return;
        if (ck[x] || ck[y]) par[y] = x, ck[x] = ck[y] = 1;
        else {
            cnt++;
            par[y] = x; ck[x] = ck[y] = 1;
        }
    };
    vector<int> c = a;
    sort(c.begin(), c.end()); c.resize(unique(c.begin(), c.end()) - c.begin());
    vector<vector<int>> add(n, vector<int>());
    auto get = [&] (int x) {
        return lower_bound(c.begin(), c.end(), x) - c.begin();
    };
    for (int i = 0; i < n; i++) add[get(a[i])].emplace_back(i);
    for (int i = n - 1; i >= 0; i--) {
        for (auto &e: add[i]) {
            if (e && a[e - 1] >= a[e]) mg(e - 1, e);
            if (e != n - 1 && a[e + 1] >= a[e]) mg(e, e + 1);
        }
        ans = max(ans, cnt);
    }
    printf("%d", ans);
}

Compilation message (stderr)

gw.cpp: In function 'int main()':
gw.cpp:9:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
    9 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
gw.cpp:12:27: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |     for (auto &e: a) scanf("%d", &e);
      |                      ~~~~~^~~~~~~~~~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 6
• Subtask 3: 0 / 7
• Subtask 4: 0 / 10
• Subtask 5: 0 / 11