#include <bits/stdc++.h> using namespace std; typedef vector<int> VI; typedef vector<VI> VVI; typedef long long LL; typedef pair<int,int> PI; typedef pair<LL,LL> PLL; typedef unsigned long long ULL; typedef pair<double,double> PD; #define FOR(x, b, e) for(int x = b; x<= (e); x++) #define FORD(x, b, e) for(int x = b; x>= (e); x--) #define REP(x, n) for(int x = 0; x<(n); ++x) #define ALL(c) (c).begin(), (c).end() #define SIZE(x) ((int)(x).size()) #define PB push_back #define IN insert #define ST first #define ND second #define INF 2000000011 #define MOD 1000000007 #define MAXS 500010 LL suf[MAXS]; //odpowiednio to bedzie prefix dla {[p,p]},{[p-1,p],[p-1,p-1]} itd... LL arr[MAXS]; vector<LL> poz; int main(){ ios::sync_with_stdio(0); cin.tie(0); int n; cin>>n; int p=0; FOR(i,1,n){ cin>>arr[i]; if(arr[i]!=0){ poz.PB(i); p++; } } FORD(i,n,1) suf[i]=suf[i+1]+arr[i]; if(suf[1]<0){ cout<<"-1\n"; return 0; } if(p==0){ cout<<"0\n"; return 0; } map<LL,LL> mapa; LL digDp=INF; FORD(i,p-1,0){ if(suf[poz[i]]>=0){ digDp=0; auto it=mapa.upper_bound(suf[poz[i]]);//szukamy {s,val}, t. ze s>suf[poz[i]] if(it!=mapa.begin()){ it--; //wtedy staje sie ze s<=suf[poz[i]] digDp=it->second; } if(i){ LL val=digDp+poz[i]-poz[i-1]; if(mapa.empty()) mapa.insert({suf[poz[i]],val}); else{ it=mapa.upper_bound(suf[poz[i]]); if(it!=mapa.begin()){ it--; if(it->second>=val) continue; it++; } while(it!=mapa.end()&&it->second<=val) it=mapa.erase(it); mapa.insert({suf[poz[i]],val}); } } } } cout<<poz[p-1]-poz[0]-digDp<<"\n"; }
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 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 | #include <bits/stdc++.h> using namespace std; typedef vector<int> VI; typedef vector<VI> VVI; typedef long long LL; typedef pair<int,int> PI; typedef pair<LL,LL> PLL; typedef unsigned long long ULL; typedef pair<double,double> PD; #define FOR(x, b, e) for(int x = b; x<= (e); x++) #define FORD(x, b, e) for(int x = b; x>= (e); x--) #define REP(x, n) for(int x = 0; x<(n); ++x) #define ALL(c) (c).begin(), (c).end() #define SIZE(x) ((int)(x).size()) #define PB push_back #define IN insert #define ST first #define ND second #define INF 2000000011 #define MOD 1000000007 #define MAXS 500010 LL suf[MAXS]; //odpowiednio to bedzie prefix dla {[p,p]},{[p-1,p],[p-1,p-1]} itd... LL arr[MAXS]; vector<LL> poz; int main(){ ios::sync_with_stdio(0); cin.tie(0); int n; cin>>n; int p=0; FOR(i,1,n){ cin>>arr[i]; if(arr[i]!=0){ poz.PB(i); p++; } } FORD(i,n,1) suf[i]=suf[i+1]+arr[i]; if(suf[1]<0){ cout<<"-1\n"; return 0; } if(p==0){ cout<<"0\n"; return 0; } map<LL,LL> mapa; LL digDp=INF; FORD(i,p-1,0){ if(suf[poz[i]]>=0){ digDp=0; auto it=mapa.upper_bound(suf[poz[i]]);//szukamy {s,val}, t. ze s>suf[poz[i]] if(it!=mapa.begin()){ it--; //wtedy staje sie ze s<=suf[poz[i]] digDp=it->second; } if(i){ LL val=digDp+poz[i]-poz[i-1]; if(mapa.empty()) mapa.insert({suf[poz[i]],val}); else{ it=mapa.upper_bound(suf[poz[i]]); if(it!=mapa.begin()){ it--; if(it->second>=val) continue; it++; } while(it!=mapa.end()&&it->second<=val) it=mapa.erase(it); mapa.insert({suf[poz[i]],val}); } } } } cout<<poz[p-1]-poz[0]-digDp<<"\n"; } |