Submission #402109

#	Time	Username	Problem	Language	Result	Execution time	Memory
402109		b00n0rp	Rectangles (IOI19_rect)	C++17	59 / 100	2097 ms	1048580 KiB

rect

#include "rect.h"
#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define vi vector<int>
#define pb push_back
#define REP(i,n) for(int i = 0; i < n; i++)
#define FOR(i,a,b) for(int i = a; i < b; i++)
#define FORD(i,a,b) for(int i = a; i >= b; i --)
#define pii pair<int,int>
#define F first
#define S second
#define all(v) v.begin(),v.end()
#define SZ(v) (int)v.size()
 
const ll MX = 2505;
 
ll ans = 0;
int n,m; 
int gl[MX][MX],gr[MX][MX],gu[MX][MX],gd[MX][MX];
vector<pii> row_seg[MX][MX],col_seg[MX][MX];
unordered_map<ll,int> row_map,col_map;
 
void check_rectangle(int x1,int y1,int x2,int y2){
    
    ll val1 = (y1-1)*MX*MX+(y2+1)*MX+x1;
    if(row_map.find(val1) == row_map.end()) return;
    if(row_map[val1] < x2) return;

    ll val2 = (x1-1)*MX*MX+(x2+1)*MX+y1;
    if(col_map.find(val2) == col_map.end()) return;
    if(col_map[val2] < y2) return;

    ans++;
}
 
ll count_rectangles(vector<vi> a) {
    n = a.size();
    m = a[0].size();
    if(n <= 2 or m <= 2) return 0;
    REP(i,n){
        stack<int> st;
        REP(j,m){
            gl[i][j] = gr[i][j] = gu[i][j] = gd[i][j] = -1;
        }
        REP(j,m){
            while(st.size() and a[i][st.top()] <= a[i][j]){
                gr[i][st.top()] = j;
                st.pop();
            }
            st.push(j);
        }
        while(!st.empty()) st.pop();
        FORD(j,m-1,0){
            while(st.size() and a[i][st.top()] <= a[i][j]){
                gl[i][st.top()] = j;
                st.pop();
            }
            st.push(j);
        }
        REP(j,m){
            if(gr[i][j] != -1 and gr[i][j] != j+1){
                if(row_seg[j][gr[i][j]].empty() or i-1 > row_seg[j][gr[i][j]].back().S){
                    row_seg[j][gr[i][j]].pb({i,i});
                }
                else row_seg[j][gr[i][j]].back().S++;
            }
            if(gl[i][j] != -1 and gl[i][j] != j-1 and gr[i][gl[i][j]] != j){
                if(row_seg[gl[i][j]][j].empty() or i-1 > row_seg[gl[i][j]][j].back().S){
                    row_seg[gl[i][j]][j].pb({i,i});
                }
                else row_seg[gl[i][j]][j].back().S++;
            }
        }
    }
    REP(j,m){
        stack<int> st;
        REP(i,n){
            while(st.size() and a[st.top()][j] <= a[i][j]){
                gd[st.top()][j] = i;
                st.pop();
            }
            st.push(i);
        }
        while(!st.empty()) st.pop();
        FORD(i,n-1,0){
            while(st.size() and a[st.top()][j] <= a[i][j]){
                gu[st.top()][j] = i;
                st.pop();
            }
            st.push(i);
        }
        REP(i,n){
            if(gd[i][j] != -1 and gd[i][j] != i+1){
                if(col_seg[i][gd[i][j]].empty() or j-1 > col_seg[i][gd[i][j]].back().S){
                    col_seg[i][gd[i][j]].pb({j,j});
                }
                else col_seg[i][gd[i][j]].back().S++;
            }
            if(gu[i][j] != -1 and gu[i][j] != i-1 and gd[gu[i][j]][j] != i){
                if(col_seg[gu[i][j]][i].empty() or j-1 > col_seg[gu[i][j]][i].back().S){
                    col_seg[gu[i][j]][i].pb({j,j});
                }
                else col_seg[gu[i][j]][i].back().S++;
            }
        }
    }
	REP(i,m){
		FOR(j,i+2,m){
			for(auto x:row_seg[i][j]){
				FOR(y,x.F,x.S+1){
					row_map[i*MX*MX+j*MX+y] = x.S;
				}
			}
			row_seg[i][j].clear();
		}
    }
    REP(i,n){
		FOR(j,i+2,n){
			for(auto x:col_seg[i][j]){
				FOR(y,x.F,x.S+1){
					col_map[i*MX*MX+j*MX+y] = x.S;
				}
			}
			col_seg[i][j].clear();
		}
    }
    vector<vi> bruh;
    FOR(i,1,n-1){
        FOR(j,1,m-1){
            // topleft
            if(gr[i][j-1] != -1 and gd[i-1][j] != -1){
            	bruh.pb({i,j,gd[i-1][j]-1,gr[i][j-1]-1});
            }
            // topright
            if(gl[i][j+1] != -1 and gd[i-1][j] != -1){
                bruh.pb({i,gl[i][j+1]+1,gd[i-1][j]-1,j});
            }
            // bottomleft
            if(gr[i][j-1] != -1 and gu[i+1][j] != -1){
            	bruh.pb({gu[i+1][j]+1,j,i,gr[i][j-1]-1});
            }
            // bottomright
            if(gl[i][j+1] != -1 and gu[i+1][j] != -1){
            	bruh.pb({gu[i+1][j]+1,gl[i][j+1]+1,i,j});
            }
            // clockwise
            if(gr[i][j-1] != -1 and gd[i-1][gr[i][j-1]-1] != -1){
            	bruh.pb({i,j,gd[i-1][gr[i][j-1]-1]-1,gr[i][j-1]-1});
            }
            // anti-clockwise
            if(gl[i][j+1] != -1 and gd[i-1][gl[i][j+1]+1] != -1){
            	bruh.pb({i,gl[i][j+1]+1,gd[i-1][gl[i][j+1]+1]-1,j});
            }
        }
    }
    sort(all(bruh));
    REP(i,SZ(bruh)){
    	if(i == 0 or bruh[i] != bruh[i-1]){
    		check_rectangle(bruh[i][0],bruh[i][1],bruh[i][2],bruh[i][3]);
    	}
    }
    return ans;
}

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