#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 3010;
const int INF = 1e9;
int n;
int dp[N][N];
int L[N], R[N];
vector<vector<int>> ans;
int recur(int l, int r) {
if(l == 1 && r == n) ans[l][r] = 0;
if(ans[l][r] != -1) return ans[l][r];
ans[l][r] = INF;
for(int i = l; i <= r; i++) {
if(l <= L[i] && R[i] <= r) continue;
ans[l][r] = min(ans[l][r], recur(min(l, L[i]), max(r, R[i])) + 1);
}
return ans[l][r];
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin >> n;
for(int i = 1; i <= n; i++)
cin >> L[i] >> R[i];
int mx[n + 1] = {};
for(int i = 1; i <= n; i++)
mx[i] = max(mx[i - 1], R[i]);
// if(n <= 300) {
// dp[1][n] = 0;
// for(int len = n - 1; len >= 1; len--) {
// for(int l = 1; l <= n - len + 1; l++) {
// int r = l + len - 1;
// dp[l][r] = INF;
// for(int i = l; i <= r; i++) {
// dp[l][r] = min(dp[l][r], dp[min(l, L[i])][max(r, R[i])] + 1);
// }
// }
// }
// int q;
// cin >> q;
// while(q--) {
// int x;
// cin >> x;
// cout << (dp[x][x] == INF ? -1 : dp[x][x]) << '\n';
// }
// return 0;
// }
if(n <= 2500) {
int q;
cin >> q;
int x;
cin >> x;
ans.resize(n + 10, vector<int>(n + 10, -1));
cout << recur(x, x);
return 0;
}
int q;
cin >> q;
int x, res = 0;
cin >> x;
while(x < n) {
res++;
if(mx[x] == x) {
cout << -1;
return 0;
}
x = max(x, mx[x]);
}
cout << res;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Incorrect |
1 ms |
212 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Correct |
0 ms |
212 KB |
Output is correct |
3 |
Incorrect |
1 ms |
244 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Correct |
0 ms |
212 KB |
Output is correct |
3 |
Incorrect |
1 ms |
244 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Correct |
0 ms |
212 KB |
Output is correct |
3 |
Incorrect |
1 ms |
244 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Incorrect |
1 ms |
212 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |