Submission #143040

#	Time	Username	Problem	Language	Result	Execution time	Memory
143040		HellAngel	Boat (APIO16_boat)	C++14	9 / 100	454 ms	12468 KiB

boat

#include <bits/stdc++.h>
#define int long long

using namespace std;
const int maxn = 1007;
const int somod = 1e9 + 7;
int n, m, a[maxn], b[maxn];
int precal[maxn][maxn], s[maxn][maxn], cnt[maxn];
vector<int> vt;

int BIT[maxn], ans[maxn], dp[maxn][maxn], total[maxn];

int Pow(int i, int j)
{
    if(j == 0) return 1;
    int mid = Pow(i, j / 2);
    mid = mid * mid % somod;
    if(j & 1) mid = mid * i % somod;
    return mid;
}

int32_t main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if(fopen("test.inp", "r")) freopen("test.inp", "r", stdin), freopen("test.out", "w", stdout);
    cin >> n;
    for(int i = 1; i <= n; i++)
    {
        cin >> a[i] >> b[i];
        vt.push_back(a[i]);
        vt.push_back(b[i] + 1);
    }
    sort(vt.begin(), vt.end());
    vt.erase(unique(vt.begin(), vt.end()), vt.end());
    int k = vt.size();
    k--;
    for(int i = 1; i <= k; i++)
    {
        precal[i][0] = 1;
        int Dist = vt[i] - vt[i - 1];
        precal[i][1] = Dist;
        for(int j = 2; j <= n + 1; j++)
        {
            precal[i][j] = precal[i][j - 1] * (Dist + j - 1) % somod * Pow(j, somod - 2) % somod; ///figurate number
        }
    }
    for(int i = 1; i <= n; i++)
    {
        int sum = 0;
        for(int j = 1; j <= k; j++)
        {
            int sum = 0, dem = 1;
            int gau = precal[j][dem];
            if(a[i] <= vt[j - 1] && vt[j] - 1 <= b[i])
            {
                cnt[j]++;
                for(int t = i - 1; t >= 1; t--)
                {
                    sum = (sum + gau * s[t][j - 1]) % somod;
                    if(a[t] <= vt[j - 1] && vt[j] - 1 <= b[t]) gau = (gau + precal[j][++dem] - vt[j] + vt[j - 1] + somod) % somod;
                }
                sum = (sum + precal[j][cnt[j]]) % somod;
            }
            s[i][j] = (s[i][j - 1] + sum) % somod;
        }
    }
    int ans = 0;
    for(int i = 1; i <= n; i++) ans = (ans + s[i][k]) % somod;
    cout << ans;
}

Compilation message (stderr)

boat.cpp: In function 'int32_t main()':
boat.cpp:50:13: warning: unused variable 'sum' [-Wunused-variable]
         int sum = 0;
             ^~~
boat.cpp:26:63: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     if(fopen("test.inp", "r")) freopen("test.inp", "r", stdin), freopen("test.out", "w", stdout);
                                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
boat.cpp:26:63: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]

• Subtask 1: 9 / 9
• Subtask 2: 0 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42