#define _USE_MATH_DEFINES #include <bits/stdc++.h> #ifdef LOC #include "debuglib.h" #else #define deb(...) #define DBP(...) #endif using namespace std; using ll = long long; using Vi = vector<int>; using Pii = pair<int, int>; #define pb push_back #define mp make_pair #define x first #define y second #define rep(i, b, e) for (int i = (b); i < (e); i++) #define each(a, x) for (auto& a : (x)) #define all(x) (x).begin(), (x).end() #define sz(x) int((x).size()) int main() { cin.sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(10); int n; cin >> n; vector<ll> pref = {0}; rep(i, 0, n) { int k; cin >> k; pref.pb(pref.back() + k); } if (pref[0] > pref.back()) { cout << "-1\n"; return 0; } vector<ll> dp(sz(pref)+5, INT64_MAX); rep(i, 1, sz(pref)-1) { if (pref[i] >= 0 && pref[i] <= pref.back()) { *upper_bound(all(dp), pref[i]) = pref[i]; } } int ans = n-1 - int(lower_bound(all(dp), INT64_MAX) - dp.begin()); cout << ans << '\n'; return 0; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | #define _USE_MATH_DEFINES #include <bits/stdc++.h> #ifdef LOC #include "debuglib.h" #else #define deb(...) #define DBP(...) #endif using namespace std; using ll = long long; using Vi = vector<int>; using Pii = pair<int, int>; #define pb push_back #define mp make_pair #define x first #define y second #define rep(i, b, e) for (int i = (b); i < (e); i++) #define each(a, x) for (auto& a : (x)) #define all(x) (x).begin(), (x).end() #define sz(x) int((x).size()) int main() { cin.sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(10); int n; cin >> n; vector<ll> pref = {0}; rep(i, 0, n) { int k; cin >> k; pref.pb(pref.back() + k); } if (pref[0] > pref.back()) { cout << "-1\n"; return 0; } vector<ll> dp(sz(pref)+5, INT64_MAX); rep(i, 1, sz(pref)-1) { if (pref[i] >= 0 && pref[i] <= pref.back()) { *upper_bound(all(dp), pref[i]) = pref[i]; } } int ans = n-1 - int(lower_bound(all(dp), INT64_MAX) - dp.begin()); cout << ans << '\n'; return 0; } |