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Submission #287948

# Submission time Handle Problem Language Result Execution time Memory
287948 2020-09-01T07:10:48 Z PeppaPig Discharging (NOI20_discharging) C++14
20 / 100
 173 ms 8232 KB 
#include <bits/stdc++.h>

#define long long long

using namespace std;

const int N = 1e6 + 5;

struct CHT {
    struct line {
        long m, c;
        line(long m, long c) : m(m), c(c) {}
        long f(long x) { return m * x + c; }
    };
    int ptr = 0;
    vector<line> vec;

    bool bad(line a, line b, line c) {
        return (c.c - a.c) * (a.m - b.m) <= (b.c - a.c) * (a.m - c.m);
    }

    void add(long m, long c) {
        line l(m, c);
        while(vec.size() > 1 && bad(vec[(int)vec.size() - 2], vec.back(), l))
            vec.pop_back();
        vec.emplace_back(l);
    }

    long get_ans(long x) {
        if(ptr >= (int)vec.size()) ptr = (int)vec.size() - 1;
        while(ptr + 1 < (int)vec.size() && vec[ptr + 1].f(x) < vec[ptr].f(x)) 
            ++ptr;
        return vec[ptr].f(x);
    }
} hull;

int n;
long A[N], dp[N];
vector<int> stk;

int main() {
    scanf("%d", &n);
    for(int i = n; i; i--) scanf("%lld", A + i);

    A[0] = 1e18;
    stk.emplace_back(0);
    for(int i = 1; i <= n; i++) {
        while(!stk.empty() && A[stk.back()] <= A[i])
            stk.pop_back();
        stk.emplace_back(i);
    }
    for(int i = 1; i < (int)stk.size(); i++) {
        hull.add(A[stk[i]], dp[i - 1]);
        dp[i] = hull.get_ans(stk[i]);
    }

    printf("%lld\n", dp[(int)stk.size() - 1]);

    return 0;
}

Compilation message

Discharging.cpp: In function 'int main()':
Discharging.cpp:42:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   42 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
Discharging.cpp:43:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   43 |     for(int i = n; i; i--) scanf("%lld", A + i);
      |                            ~~~~~^~~~~~~~~~~~~~~

Subtask #1
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 256 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 1 ms 256 KB Output is correct
4 Correct 0 ms 384 KB Output is correct
5 Correct 1 ms 384 KB Output is correct
6 Correct 0 ms 384 KB Output is correct
7 Correct 1 ms 384 KB Output is correct
8 Correct 1 ms 384 KB Output is correct
9 Correct 1 ms 384 KB Output is correct
10 Correct 0 ms 384 KB Output is correct
11 Correct 0 ms 384 KB Output is correct
12 Correct 0 ms 256 KB Output is correct
13 Correct 0 ms 384 KB Output is correct
14 Correct 1 ms 256 KB Output is correct

Subtask #2
0 / 13.0

# Verdict Execution time Memory Grader output
1 Incorrect 1 ms 384 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #3
0 / 25.0

# Verdict Execution time Memory Grader output
1 Incorrect 1 ms 384 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
11.0 / 11.0

# Verdict Execution time Memory Grader output
1 Correct 167 ms 8184 KB Output is correct
2 Correct 160 ms 8184 KB Output is correct
3 Correct 163 ms 8184 KB Output is correct
4 Correct 162 ms 8100 KB Output is correct
5 Correct 173 ms 8184 KB Output is correct
6 Correct 171 ms 8184 KB Output is correct
7 Correct 165 ms 8232 KB Output is correct
8 Correct 165 ms 8184 KB Output is correct
9 Correct 168 ms 8184 KB Output is correct
10 Correct 165 ms 8184 KB Output is correct

Subtask #5
0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 256 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 1 ms 256 KB Output is correct
4 Correct 0 ms 384 KB Output is correct
5 Correct 1 ms 384 KB Output is correct
6 Correct 0 ms 384 KB Output is correct
7 Correct 1 ms 384 KB Output is correct
8 Correct 1 ms 384 KB Output is correct
9 Correct 1 ms 384 KB Output is correct
10 Correct 0 ms 384 KB Output is correct
11 Correct 0 ms 384 KB Output is correct
12 Correct 0 ms 256 KB Output is correct
13 Correct 0 ms 384 KB Output is correct
14 Correct 1 ms 256 KB Output is correct
15 Incorrect 1 ms 384 KB Output isn't correct
16 Halted 0 ms 0 KB -

Subtask #6
0 / 28.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 256 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 1 ms 256 KB Output is correct
4 Correct 0 ms 384 KB Output is correct
5 Correct 1 ms 384 KB Output is correct
6 Correct 0 ms 384 KB Output is correct
7 Correct 1 ms 384 KB Output is correct
8 Correct 1 ms 384 KB Output is correct
9 Correct 1 ms 384 KB Output is correct
10 Correct 0 ms 384 KB Output is correct
11 Correct 0 ms 384 KB Output is correct
12 Correct 0 ms 256 KB Output is correct
13 Correct 0 ms 384 KB Output is correct
14 Correct 1 ms 256 KB Output is correct
15 Incorrect 1 ms 384 KB Output isn't correct
16 Halted 0 ms 0 KB -