| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 154445 | crackersamdjam | Rectangles (IOI19_rect) | C++14 | 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.
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse4,popcnt,abm,mmx,tune=native")
#include <bits/stdc++.h>
#define gc getchar_unlocked()
#define pc(x) putchar_unlocked(x)
template<typename T> void scan(T &x){x = 0;register bool _=0;register T c=gc;_=c==45;c=_?gc:c;while(c<48||c>57)c=gc;for(;c<48||c>57;c=gc);for(;c>47&&c<58;c=gc)x=(x<<3)+(x<<1)+(c&15);x=_?-x:x;}
template<typename T> void printn(T n){register bool _=0;_=n<0;n=_?-n:n;char snum[65];int i=0;do{snum[i++]=n%10+48;n/= 10;}while(n);--i;if (_)pc(45);while(i>=0)pc(snum[i--]);}
template<typename First, typename ... Ints> void scan(First &arg, Ints&... rest){scan(arg);scan(rest...);}
template<typename T> void print(T n){printn(n);pc(10);}
template<typename First, typename ... Ints> void print(First arg, Ints... rest){printn(arg);pc(32);print(rest...);}
using namespace std;
const int MM = 2502;
int n, m, ans;
int first[MM], last[MM], bit[MM];
stack<pair<int, int>> st;
map<int, int, greater<int>> hor[MM][MM], vert[MM][MM];
//stores either right or down endpoint, and "dp" val
void update(int i, int v){
for(i = MM-1-i; i < MM; i += i&-i)
bit[i] += v;
}
int query(int i){
int ret = 0;
for(i = MM-1-i; i; i -= i&-i)
ret += bit[i];
return ret;
}
void clear(){
while(!st.empty())
st.pop();
}
vector<pair<int, int>> vec(MM);
vector<int> unupdate;
long long count_rectangles(vector<vector<int>> a){
n = a.size(), m = a[0].size();
for(int i = 0; i < n; i++){
clear();
for(int j = 0; j < m; j++){
//help remove duplicate
while(!st.empty() && st.top().first < a[i][j])
st.pop();
first[j] = (st.empty() || st.top().first == a[i][j]) ? -1 : st.top().second;
st.push({a[i][j], j});
}
clear();
for(int j = m-1; j >= 0; j--){
while(!st.empty() && st.top().first <= a[i][j])
st.pop();
last[j] = st.empty() ? -1 : st.top().second;
st.push({a[i][j], j});
}
for(int j = 0; j < m; j++){
if(first[j] == -1 || last[j] == -1)
continue;
first[j]++, last[j]--;
hor[i][first[j]][last[j]] = 1;
}
}
for(int j = 0; j < m; j++){
clear();
for(int i = 0; i < n; i++){
//help remove duplicate
while(!st.empty() && st.top().first < a[i][j])
st.pop();
first[i] = (st.empty() || st.top().first == a[i][j]) ? -1 : st.top().second;
st.push({a[i][j], i});
}
clear();
for(int i = n-1; i >= 0; i--){
while(!st.empty() && st.top().first <= a[i][j])
st.pop();
last[i] = st.empty() ? -1 : st.top().second;
st.push({a[i][j], i});
}
for(int i = 0; i < n; i++){
if(first[i] == -1 || last[i] == -1)
continue;
first[i]++, last[i]--;
vert[first[i]][j][last[i]] = 1;
}
}
for(int i = n-1; i >= 0; i--){
for(int j = m-1; j >= 0; j--){
for(auto &x: hor[i][j])
if(hor[i+1][j].count(x.first))
x.second += hor[i+1][j][x.first];
for(auto &x: vert[i][j])
if(vert[i][j+1].count(x.first))
x.second += vert[i][j+1][x.first];
for(int x: unupdate)
update(x, -1);
unupdate.clear();
vec.clear();
for(auto &x: hor[i][j])
vec.push_back({x.first-j+1, x.second}); //adjust
sort(vec.begin(), vec.end(), [](auto &x, auto &y){
return x.second > y.second;
});
//now sorted by y
//printf("go "); print(i, j);
int l = 0;
for(auto &b: vert[i][j]){
int bf = b.first-i+1;
while(l < vec.size() && bf <= vec[l].second){
unupdate.push_back(vec[l].first);
update(vec[l++].first, 1);
//printf("up "); print(vec[l++].first);
}
ans += query(b.second);
//printf("q "); print(b.second, query(b.second));
}
//if(x.first-j+1 <= y.second && y.first-i+1 <= x.second)
/*
* sort hor and vert by y reversed
* loop through vert with l ptr for hor
* while hor[l].y >= vert.y, push hor[l++].x into bit
* answer += query_greater_than_equals(vert[i].x)
*/
//okay so
//print(i, j, hor[i][j].size(), vert[i][j].size());
/*
for(auto &x: hor[i][j]){
for(auto &y: vert[i][j]){
if(x.first-j+1 <= y.second && y.first-i+1 <= x.second){
ans++;
//print(-1, i, j, y.first, x.first);
}
}
}
*/
}
}
return ans;
}
#ifndef ONLINE_JUDGE
int main(){
//print(count_rectangles({{3, 2, 2, 3}}));
print(count_rectangles({{4, 8, 7, 5, 6},
{7, 4, 10, 3, 5},
{9, 7, 20, 14, 2},
{9, 14, 7, 3, 6},
{5, 7, 5, 2, 7},
{4, 5, 13, 5, 6}})
);
return 0;
}
#endif
/*
* in a row, for every point, get 1st left > and 1st right greater
* this will get all possible
*
* using mono stack
*
*
* sort row segments
* starting at point i, on row j
* for each (i, r), dp for how long can go down
*
* then do same for vertical
*
* when it works is when: vert_seg <= dp_vert[hor_seg] and hor_seg <= dp_hor[vert_seg]
*
* sort hor and vert by y reversed
* loop through vert with l ptr for hor
* while hor[l] >= y, push hor[l++].x into bit
* answer += query_greater_than_equals(vert[i].x)
*
* vertical <= NM
* horizontal <= NM
* time complexity vert * log(hor) = NM log(NM)
*/