Submission #937440

#	Time	Username	Problem	Language	Result	Execution time	Memory
937440		GrindMachine	Rectangles (IOI19_rect)	C++17	25 / 100	284 ms	233628 KiB

rect

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*

read some solutions long back, remember some ideas from there

*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

#include "rect.h"

template<typename T>
struct fenwick {
    int siz;
    vector<T> tree;

    fenwick() {

    }

    fenwick(int n) {
        siz = n;
        tree = vector<T>(n + 1);
    }

    int lsb(int x) {
        return x & -x;
    }

    void build(vector<T> &a, int n) {
        for (int i = 1; i <= n; ++i) {
            int par = i + lsb(i);
            tree[i] += a[i];

            if (par <= siz) {
                tree[par] += tree[i];
            }
        }
    }

    void pupd(int i, T v) {
    	i++;
        while (i <= siz) {
            tree[i] += v;
            i += lsb(i);
        }
    }

    T sum(int i) {
    	i++;
        T res = 0;

        while (i) {
            res += tree[i];
            i -= lsb(i);
        }

        return res;
    }

    T query(int l, int r) {
        if (l > r) return 0;
        T res = sum(r) - sum(l - 1);
        return res;
    }
};

long long count_rectangles(std::vector<std::vector<int> > a) {
	short n = sz(a), m = sz(a[0]);
	if(n <= 2 or m <= 2) return 0;

	vector<pair<short,short>> up[n][m];
	short ptr = 0;

	rep(j,m){
		stack<short> st;
		rep(i,n){
			bool eq = false;
			while(!st.empty() and a[i][j] >= a[st.top()][j]){
				short k = st.top();
				st.pop();
				if(a[i][j] == a[k][j]){
					eq = true;
				}
				if(i-k >= 2){
					up[i][j].pb({k,ptr++});
				}
			}

			if(!st.empty() and !eq){
				short k = st.top();
				if(i-k >= 2){
					up[i][j].pb({k,ptr++});
				}
			}

			st.push(i);
		}
	}

	vector<short> farthest(ptr);
	map<array<short,3>,short> mp;

	rev(j,m-1,0){
		rep(i,n){
			for(auto [k,ptr] : up[i][j]){
				array<short,3> ar = {j,k,i};
				array<short,3> want = {j+1,k,i};
				if(mp.count(want)){
					farthest[ptr] = farthest[mp[want]];
				}
				else{
					farthest[ptr] = j;
				}

				mp[ar] = ptr;
			}
		}
	}

	short prev_occ[m][m], first_occ[m][m];
	memset(prev_occ,-1,sizeof prev_occ);
	memset(first_occ,-1,sizeof first_occ);

	ll ans = 0;
	vector<short> queries[ptr];

	rep1(i,n-2){
		stack<short> st;
		vector<pair<short,short>> good;
		rep(j,m){
			bool eq = false;
			while(!st.empty() and a[i][j] >= a[i][st.top()]){
				short k = st.top();
				st.pop();
				if(a[i][j] == a[i][k]){
					eq = true;
				}
				if(j-k >= 2){
					good.pb({k,j});
				}
			}

			// cout << j << endl;
			// cout << eq << endl;
			// auto st_copy = st;
			// while(!st_copy.empty()){
			// 	cout << st_copy.top() << " ";
			// 	st_copy.pop();
			// }
			// cout << endl;

			if(!st.empty() and !eq){
				short k = st.top();
				if(j-k >= 2){
					// cout << k << " " << j << endl;
					good.pb({k,j});
				}
			}

			st.push(j);
		}

		for(auto [l,r] : good){
			if(prev_occ[l][r] != i-1){
				first_occ[l][r] = i;
			}

			prev_occ[l][r] = i;

			short lo = 0, hi = sz(up[i+1][l+1])-1;
			short pos = -1;

			while(lo <= hi){
				short mid = (lo+hi) >> 1;
				if(up[i+1][l+1][mid].ff >= first_occ[l][r]-1){
					pos = mid;
					lo = mid+1;
				}
				else{
					hi = mid-1;
				}
			}

			if(pos != -1){
				short ind = up[i+1][l+1][pos].ss;
				queries[ind].pb(r);
			}

			/*

			for(auto [k,ptr] : up[i+1][l+1]){
				if(k >= first_occ[l][r]-1){
					if(farthest[ptr] >= r-1){
						ans++;
					}
				}
				else{
					break;
				}
			}

			*/
		}
	}

	fenwick<short> fenw(m);

	rep(i,n){
		rep(j,m){
			for(auto [k,ptr] : up[i][j]){
				fenw.pupd(farthest[ptr],1);
				trav(r,queries[ptr]){
					ans += fenw.query(r-1,m-1);
				}
			}

			for(auto [k,ptr] : up[i][j]){
				fenw.pupd(farthest[ptr],-1);
			}
		}
	}

	/*

	ll oans = 0;

	rep1(i1,n-2){
		rep1(j1,m-2){
			for(short i2 = i1; i2 < n-1; ++i2){
				for(short j2 = j1; j2 < m-1; ++j2){
					bool ok = true;
					for(short r = i1; r <= i2; ++r){
						for(short c = j1; c <= j2; ++c){
							if(a[r][c] >= min({a[i1-1][c],a[i2+1][c],a[r][j1-1],a[r][j2+1]})){
								ok = false;
								break;
							}
						}
						if(!ok) break;
					}

					if(ok){
						oans++;
						cout << i1 << " " << j1 << " " << i2 << " " << j2 << endl;
					}
				}
			}
		}
	}
	
	*/
	
	// cout << ans << endl;
	// cout << oans << endl;
	// cout << endl;

	// assert(ans == oans);

	return ans;
}

Compilation message (stderr)

rect.cpp: In function 'long long int count_rectangles(std::vector<std::vector<int> >)':
rect.cpp:157:26: warning: narrowing conversion of 'j' from 'int' to 'short int' [-Wnarrowing]
  157 |     array<short,3> ar = {j,k,i};
      |                          ^
rect.cpp:157:30: warning: narrowing conversion of 'i' from 'int' to 'short int' [-Wnarrowing]
  157 |     array<short,3> ar = {j,k,i};
      |                              ^
rect.cpp:158:29: warning: narrowing conversion of '(j + 1)' from 'int' to 'short int' [-Wnarrowing]
  158 |     array<short,3> want = {j+1,k,i};
      |                            ~^~
rect.cpp:158:34: warning: narrowing conversion of 'i' from 'int' to 'short int' [-Wnarrowing]
  158 |     array<short,3> want = {j+1,k,i};
      |                                  ^

• Subtask 1: 8 / 8
• Subtask 2: 7 / 7
• Subtask 3: 0 / 12
• Subtask 4: 0 / 22
• Subtask 5: 10 / 10
• Subtask 6: 0 / 13
• Subtask 7: 0 / 28