Submission #1027820

#	Time	Username	Problem	Language	Result	Execution time	Memory
1027820		mansur	Flooding Wall (BOI24_wall)	C++17	0 / 100	499 ms	1048576 KiB

Main

#include<bits/stdc++.h>

using namespace std;

#define rall(s) s.rbegin(), s.rend()
#define all(s) s.begin(), s.end()
#define sz(s) (int)s.size()
#define s second
#define f first

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

const int N = 1e6, mod = 1e9 + 7;
const int inf = 1e9;

void solve() {
	int n;
	cin >> n;
	int a[n + 1][2];
	for (int i = 1; i <= n; i++) cin >> a[i][0];
	for (int i = 1; i <= n; i++) cin >> a[i][1];
	for (int i = 1; i <= n; i++) {
		if (a[i][1] < a[i][0]) swap(a[i][1], a[i][0]);	
	}
	int dp[n + 1][1001], cnt[n + 1][1001];
	memset(dp, 0, sizeof(dp));
	memset(cnt, 0, sizeof(cnt));
	cnt[1][0] = 1;
	for (int i = 1; i < n; i++) {
		for (int x = 0; x <= 1000; x++) {
		    int v = a[i][0];
		    if (v < x) {
		    	int val = (cnt[i][x] * 1ll * (x - v)) % mod;
		    	dp[i + 1][x] = (dp[i + 1][x] + (dp[i][x] + val) % mod) % mod;
		    	cnt[i + 1][x] = (cnt[i + 1][x] + cnt[i][x]) % mod;
		    }else {
		    	cnt[i + 1][v] = (cnt[i + 1][v] + cnt[i][x]) % mod;
		    	dp[i + 1][v] = (dp[i + 1][v] + dp[i][x]) % mod;
		    }
		    v = a[i][1];
		    if (v < x) {
		    	int val = (cnt[i][x] * 1ll * (x - v)) % mod;
		    	dp[i + 1][x] = (dp[i + 1][x] + (dp[i][x] + val) % mod) % mod;
		    	cnt[i + 1][x] = (cnt[i + 1][x] + cnt[i][x]) % mod;
		    }else {
		    	cnt[i + 1][v] = (cnt[i + 1][v] + cnt[i][x]) % mod;
				dp[i + 1][v] = (dp[i + 1][v] + dp[i][x]) % mod;
			}
		}
	}
	int pd[n + 1][1001], ct[n + 1][1001];
	memset(pd, 0, sizeof(pd));
	memset(ct, 0, sizeof(ct));
	ct[n][0] = 1;
	for (int i = n; i > 1; i--) {
		for (int x = 0; x <= 1000; x++) {
		    int v = a[i][0];
		    if (v < x) {
		    	int val = (ct[i][x] * 1ll * (x - v)) % mod;
		    	pd[i - 1][x] = (pd[i - 1][x] + (pd[i][x] + val) % mod) % mod;
		    	ct[i - 1][x] = (ct[i - 1][x] + ct[i][x]) % mod;
		    }else {
		    	ct[i - 1][v] = (ct[i - 1][v] + ct[i][x]) % mod;
		    	pd[i - 1][v] = (pd[i - 1][v] + pd[i][x]) % mod;
		    }
		    v = a[i][1];
		    if (v < x) {
		    	int val = (ct[i][x] * 1ll * (x - v)) % mod;
		    	pd[i - 1][x] = (pd[i - 1][x] + (pd[i][x] + val) % mod) % mod;
		    	ct[i - 1][x] = (ct[i - 1][x] + ct[i][x]) % mod;
		    }else {
		    	ct[i - 1][v] = (ct[i - 1][v] + ct[i][x]) % mod;
				pd[i - 1][v] = (pd[i - 1][v] + pd[i][x]) % mod;
			}
		}
	}
	int ans = 0;
	for (int i = 1; i <= n; i++) {
	 	int v = a[i][0];
	 	for (int x = 0; x <= v; x++) {
	 		ans = (ans + dp[i][x]) % mod;
	 		if (x < v) ans = (ans + pd[i][x]) % mod;
	 	}
	 	v = a[i][1];
	 	for (int x = 0; x <= v; x++) {
	 		ans = (ans + dp[i][x]) % mod;
	 		if (x < v) ans = (ans + pd[i][x]) % mod;
	 	}
	}
	cout << ans;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	solve();
}

• Subtask 1: 0 / 8
• Subtask 2: 0 / 17
• Subtask 3: 0 / 19
• Subtask 4: 0 / 14
• Subtask 5: 0 / 12
• Subtask 6: 0 / 30