| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1009530 | boris_mihov | Rectangles (IOI19_rect) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "rect.h"
#include <algorithm>
#include <iostream>
#include <numeric>
#include <cassert>
#include <vector>
#include <stack>
typedef long long llong;
const short MAXLOG = 12;
const short MAXN = 2500 + 10;
const int INF = 1e8;
short n, m;
char getLOG[MAXN];
struct SparseMIN
{
short sparse[MAXN][MAXLOG];
short len;
void build(short a[], short length)
{
len = length;
for (int i = 1 ; i <= len ; ++i)
{
sparse[i][0] = a[i];
}
for (int lg = 1 ; (1 << lg) <= len ; ++lg)
{
for (int i = 1 ; i + (1 << lg) - 1 <= len ; ++i)
{
sparse[i][lg] = std::min(sparse[i][lg - 1], sparse[i + (1 << lg - 1)][lg - 1]);
}
}
}
short findMIN(short &l, short &r)
{
char lg = getLOG[r - l + 1];
return std::min(sparse[l][lg], sparse[r - (1 << lg) + 1][lg]);
}
};
struct SparseMAX
{
short sparse[MAXN][MAXLOG];
short len;
void build(short a[], short length)
{
len = length;
for (int i = 1 ; i <= len ; ++i)
{
sparse[i][0] = a[i];
}
for (int lg = 1 ; (1 << lg) <= len ; ++lg)
{
for (int i = 1 ; i + (1 << lg) - 1 <= len ; ++i)
{
sparse[i][lg] = std::max(sparse[i][lg - 1], sparse[i + (1 << lg - 1)][lg - 1]);
}
}
}
short findMAX(short &l, short &r)
{
char lg = getLOG[r - l + 1];
return std::max(sparse[l][lg], sparse[r - (1 << lg) + 1][lg]);
}
};
short a[MAXN][MAXN]; // >
short b[MAXN][MAXN]; // v
short c[MAXN][MAXN]; // <
short d[MAXN][MAXN]; // ^
int t[MAXN][MAXN];
short cpy[MAXN];
SparseMIN sparseRD[MAXN];
SparseMAX sparseRU[MAXN];
SparseMIN sparseCL[MAXN];
SparseMAX sparseCR[MAXN];
std::vector <short> possibleColE[MAXN][MAXN];
std::vector <short> possibleRowE[MAXN][MAXN];
bool isOK(short rowB, short colB, short rowE, short colE)
{
if (sparseRD[rowB].findMIN(colB + 1, colE - 1) < rowE) return false;
if (sparseRU[rowE].findMAX(colB + 1, colE - 1) > rowB) return false;
if (sparseCL[colB].findMIN(rowB + 1, rowE - 1) < colE) return false;
if (sparseCR[colE].findMAX(rowB + 1, rowE - 1) > colB) return false;
return true;
}
llong count_rectangles(std::vector <std::vector<int>> _a)
{
n = _a.size(); m = _a[0].size();
for (short i = 0 ; i < n ; ++i)
{
for (short j = 0 ; j < m ; ++j)
{
t[i + 1][j + 1] = _a[i][j];
}
}
for (short i = 0 ; i <= n + 1 ; ++i)
{
t[i][0] = t[i][m + 1] = INF;
}
for (short i = 0 ; i <= m + 1 ; ++i)
{
t[0][i] = t[n + 1][i] = INF;
}
std::stack <int> st;
for (short i = 1 ; i <= n ; ++i)
{
while (st.size()) st.pop(); st.push(m + 1);
for (short j = m ; j >= 1 ; --j)
{
while (t[i][j] > t[i][st.top()])
{
st.pop();
}
a[i][j] = st.top();
st.push(j);
}
while (st.size()) st.pop(); st.push(0);
for (short j = 1 ; j <= m ; ++j)
{
while (t[i][j] > t[i][st.top()])
{
st.pop();
}
c[i][j] = st.top();
st.push(j);
}
}
for (short i = 1 ; i <= m ; ++i)
{
while (st.size()) st.pop(); st.push(n + 1);
for (short j = n ; j >= 1 ; --j)
{
while (t[j][i] > t[st.top()][i])
{
st.pop();
}
b[j][i] = st.top();
st.push(j);
}
while (st.size()) st.pop(); st.push(0);
for (short j = 1 ; j <= n ; ++j)
{
while (t[j][i] > t[st.top()][i])
{
st.pop();
}
d[j][i] = st.top();
st.push(j);
}
}
for (short i = 1 ; i <= std::max(n, m) ; ++i)
{
getLOG[i] = getLOG[i - 1];
if ((1 << getLOG[i] + 1) < i) getLOG[i]++;
}
for (short i = 1 ; i <= n ; ++i)
{
sparseRD[i].build(b[i], m);
sparseRU[i].build(d[i], m);
}
for (short i = 1 ; i <= m ; ++i)
{
for (short j = 1 ; j <= n ; ++j)
{
cpy[j] = a[j][i];
}
sparseCL[i].build(cpy, n);
for (short j = 1 ; j <= n ; ++j)
{
cpy[j] = c[j][i];
}
sparseCR[i].build(cpy, n);
}
for (short i = 2 ; i <= n ; ++i)
{
for (short j = 2 ; j <= m ; ++j)
{
if (d[i][j] < i - 1) possibleRowE[d[i][j]][j - 1].push_back(i);
if (c[i][j] < j - 1) possibleColE[i - 1][c[i][j]].push_back(j);
}
}
for (short i = 2 ; i <= n ; ++i)
{
for (short j = 2 ; j <= m ; ++j)
{
if (i < b[i - 1][j] && b[i - 1][j] != n + 1 && (possibleRowE[i][j].empty() || possibleRowE[i][j].back() != b[i - 1][j])) possibleRowE[i - 1][j - 1].push_back(b[i - 1][j]);
if (j < a[i][j - 1] && a[i][j - 1] != m + 1 && (possibleColE[i][j].empty() || possibleColE[i][j].back() != a[i][j - 1])) possibleColE[i - 1][j - 1].push_back(a[i][j - 1]);
}
}
int answer = 0;
for (short rowB = 1 ; rowB + 1 < n ; ++rowB)
{
for (short colB = 1 ; colB + 1 < m ; ++colB)
{
for (short &rowE : possibleRowE[rowB][colB])
{
for (short &colE : possibleColE[rowB][colB])
{
answer += isOK(rowB, colB, rowE, colE);
}
}
}
}
return answer;
}