Submission #318299

#	Time	Username	Problem	Language	Result	Execution time	Memory
318299		ryangohca	Discharging (NOI20_discharging)	C++17	100 / 100	446 ms	25828 KiB

Discharging

#include <bits/stdc++.h>
#define int long long
using namespace std;
int nums[1000001], dp[1000001];
deque<pair<int,int> > dq;
int f(pair<int,int> line, int x){
     return line.first*x + line.second;
}
int query(int x){
    while(dq.size()>1){ //to prevent seg fault when accessing dq[1]
        if(f(dq[0],x)<f(dq[1],x)) //the next line is better
            dq.pop_front(); //remove useless line
        else break;
    }
    return f(dq[0],x);
}
double intersect(int m1, int c1, int m2, int c2){
      return (double)(c2-c1)/(m1-m2);
}
double intersect(pair<int,int> p1, pair<int,int> p2){
      return intersect(p1.first,p1.second,p2.first,p2.second);
}
void insert(int m,int c) {//insert line y=mx+c
     pair<int,int> line = make_pair(m,c);
     while (dq.size()>1) { //to prevent seg fault
         int s = dq.size();
         if (intersect(dq[s-1], line) <= intersect(dq[s-2], line))
            dq.pop_back(); //removes useless line
        else break;
     }
     dq.push_back(line);
}
main(){
    int n; cin >> n;
    for (int i = 1; i <= n; i++){
        dp[i] = 1e16;
        cin >> nums[i];
        nums[i] = max(nums[i], nums[i - 1]);
    }
    for (int i = 1; i <= n; i++){
        insert(i, -dp[i - 1]);
        dp[i] = -query(nums[i]) + nums[i] * n + nums[i];
        /*
        for (int j = 1; j <= i; j++){
            dp[i] = min(dp[i], - nums[i] * j + dp[j - 1] + nums[i] * n + nums[i]));
        }
        */
    }
    cout << dp[n] << '\n';
}

Compilation message (stderr)

Discharging.cpp:33:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   33 | main(){
      |      ^

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 25 / 25
• Subtask 4: 11 / 11
• Subtask 5: 14 / 14
• Subtask 6: 28 / 28