Submission #252017

#	Time	Username	Problem	Language	Result	Execution time	Memory
252017		DS007	Boat (APIO16_boat)	C++14	9 / 100	980 ms	20180 KiB

boat

#include <bits/stdc++.h>
using namespace std;
#define int long long

const int N = 500, mod = 1e9 + 7;
int a[N], b[N];
int dp[2][N * N * 3];
int n;

int solveTestCase() {
    cin >> n;
    for (int i = 0; i < n; i++)
        cin >> a[i] >> b[i];

    vector<int> v = {0};
    for (int i = 0; i < n; i++) {
        for (int j = 0; j <= n; j++)
            v.push_back(a[i] + j), v.push_back(a[i] - j), v.push_back(b[i] + j), v.push_back(b[i] - j);
    }

    sort(v.begin(), v.end());
    v.erase(unique(v.begin(), v.end()), v.end());

    for (int i = 0; i < n; i++) {
        a[i] = lower_bound(v.begin(), v.end(), a[i]) - v.begin();
        b[i] = lower_bound(v.begin(), v.end(), b[i]) - v.begin();
    }

    for (int i = a[0]; i <= b[0]; i++)
        dp[0][i] = 1;

    for (int i = 1; i < n; i++) {
        int sum = 1;
        for (int j = 0; j < a[i]; j++)
            dp[i%2][j] = dp[(i - 1)%2][j], sum += dp[(i - 1)%2][j], sum %= mod;
        for (int j = b[i] + 1; j < N * N * 3; j++)
            dp[i%2][j] = dp[(i - 1)%2][j];

        for (int j = a[i]; j <= b[i]; j++)
            sum +=  dp[(i - 1)%2][j], sum %= mod, dp[i%2][j] = sum;
    }

    int ans = 0;
    for (int i = 1; i < N * N * 3; i++)
        ans += dp[(n - 1)%2][i], ans %= mod;

    cout << ans;
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int t = 1;
    //cin >> t;
    while (t--)
        solveTestCase();
}

Compilation message (stderr)

boat.cpp: In function 'long long int solveTestCase()':
boat.cpp:48:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^

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