Submission #598619

#	Time	Username	Problem	Language	Result	Execution time	Memory
598619		definitelynotmee	Fountain Parks (IOI21_parks)	C++17	Compilation error	0 ms	0 KiB

parks

#include "parks.h"
#include<bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define all(x) x.begin(), x.end()
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
template<typename t>
using matrix = vector<vector<t>>;


int construct_roads(std::vector<int> x, std::vector<int> y) {
    if (x.size() == 1) {
	build({}, {}, {}, {});
        return 1;
    }
    int n = x.size();
    std::vector<int> u, v, a, b;

    int dx[]{1,0,-1,0};
    int dy[]{0,1,0,-1};

    vector<int> pai(n);
    int comp = n;
    iota(all(pai),0);

    auto find =[&](int id, auto f){
        if(pai[id] = id)
            return id;
        return pai[id] = f(pai[id],f);
    };
    auto onion =[&](int a, int b){
        pa = find(a,find);
        pb = find(b,find);
        if(pa != pb){
            comp--;
            u.push_back(a);
            v.push_back(b);
        }
    };
    map<pii,int> fount;

    for(int i = 0; i < n; i++)
        fount[{x[i],y[i]}] = i;

    for(int i = 0; i < n; i++){
        for(int j = 0; j < 4; j++){
            int xi = x[i] + dx[j]*2, yi = y[i]+dy[j]*2;
            if(fount.count({xi,yi}))
                onion(i,fount[{xi,yi}]);
        }
    }
    if(comp > 1)
        return 0;

    set<pii> bench;

    for(int i = 0; i < n-1; i++){
        int cx = (x[u[i]]+x[v[i]])>>1, cy = (y[u[i]]+y[v[i]])>>1;
        bool ok = 0;
        for(int j = 0; j < 4; j++){
            int xi = x[i] + dx[j], yi = y[i]+dy[j];
            if((xi&1)||(yi&1))
                continue;
            if(!bench.count({xi,yi})){
                a.push_back(xi);
                b.push_back(yi);
                ok = 1;
                break;
            }
        }
        if(!ok)
            return 0;
    }

    return 1;
}

Compilation message (stderr)

parks.cpp: In lambda function:
parks.cpp:35:9: error: 'pa' was not declared in this scope; did you mean 'pai'?
   35 |         pa = find(a,find);
      |         ^~
      |         pai
parks.cpp: In instantiation of 'construct_roads(std::vector<int>, std::vector<int>)::<lambda(int, auto:23)> [with auto:23 = construct_roads(std::vector<int>, std::vector<int>)::<lambda(int, auto:23)>]':
parks.cpp:35:25:   required from here
parks.cpp:30:20: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   30 |         if(pai[id] = id)
parks.cpp:36:9: error: 'pb' was not declared in this scope; did you mean 'b'?
   36 |         pb = find(b,find);
      |         ^~
      |         b
parks.cpp: In function 'int construct_roads(std::vector<int>, std::vector<int>)':
parks.cpp:61:13: warning: unused variable 'cx' [-Wunused-variable]
   61 |         int cx = (x[u[i]]+x[v[i]])>>1, cy = (y[u[i]]+y[v[i]])>>1;
      |             ^~
parks.cpp:61:40: warning: unused variable 'cy' [-Wunused-variable]
   61 |         int cx = (x[u[i]]+x[v[i]])>>1, cy = (y[u[i]]+y[v[i]])>>1;
      |                                        ^~