【202006-1】线性分类器

Attention：

①注意vector的变量
②注意flag变量的初始化

#include<bits/stdc++.h>
using namespace std;

const int maxn = 1010;

struct node{
    int x, y;

    node(int x, int y) : x(x), y(y) {}
};

vector<node>A, B;

int main()
{
    ios::sync_with_stdio(false);

    int n, m;
    cin >> n >> m;
    
    int x, y;
    char z;
    for(int i = 1; i <= n; ++i){
        cin >> x >> y >> z;
        node fresh(x,y);
        if(z == 'A') A.emplace_back(fresh);
        else B.emplace_back(fresh);
    }

    int a, b, c, flag = 1;
    for(int i = 1; i <= m; ++i){
        flag = 1;
        cin >> a >> b >> c;

        int A_part = a + A.begin()->x * b + A.begin()->y * c > 0;
        int B_part = a + B.begin()->x * b + B.begin()->y * c > 0;

        for(const auto&x : A){
            if(a + x.x * b + x.y * c > 0 != A_part)
                flag = 0;
        }

        for(const auto&x : B){
            if(a + x.x * b + x.y * c > 0 != B_part)
                flag = 0;
        } 

        if(flag) cout << "Y" << "e"<< "s" << "\n";
        else cout << "N" << "o" << "\n";
    }
    return 0;
}