#include <iostream>
#include <algorithm>
#include <vector>
#include <chrono>
#include <time.h>
#include <stdio.h>
#include <iomanip>
using namespace std;

//下三角矩阵
const int Row = 4;
const int Col = 4;
float _Matrix[Row][Col];
float vec[Col];
float res[Row];
float* Triangular;
#define DEBUG
void init()
{
    Triangular = new float[Row * Col];
    for (int i = 0; i < Row; i++)
    {
        for (int j = 0; j <= i; j++)
        {
            _Matrix[i][j] = _Matrix[j][i] = rand() % 100;
            int t_row = max(i, j);
            int t_col = min(i, j);
            //下三角矩阵的存储是 max(i, j) * (max(i, j) + 1) / 2 + min(i, j) 是原矩阵下标为(i, j)的元素
            Triangular[(t_row + 1) * t_row / 2 + t_col] = _Matrix[i][j];
        }
    }
    for (int i = 0; i < Col; i++)
    {
        vec[i] = rand() % 100;
    }

#ifdef DEBUG
    cout << "vec is" << endl;
    for (int i = 0; i < Col; i++)
    {
        cout << vec[i] << ' ';
    }
    cout << endl;
    cout << "this is matrix" << endl;
    for (int i = 0; i < Row; i++)
    {
        for (int j = 0; j < Col; j++)
        {
            cout << setw(5)<< _Matrix[i][j];
        }
        cout << endl;
    }
#endif 


}
void t()
{
    float r[Row];
    memset(r, 0, sizeof(r));
    for (int i = 0; i < Row; i++)
    {
        for (int j = 0; j < Col; j++)
        {
            r[i] += _Matrix[i][j] * vec[j];
        }
    }
#ifdef DEBUG
    cout << "result test is " << endl;
    for (int i = 0; i < Row; i++)
    {
        cout << r[i] << ' ';
    }
    cout << endl;
#endif // DEBUG

}
void triangular(float* v, float* _matrix, int Row, int Col, float* r)
{
    for (int row = 0; row < Row; row++)
    {
        float sum = 0;
        for (int col = 0; col < Col; col++)
        {
            int t_row = max(row, col);
            int t_col = min(row, col);
            sum += _matrix[(t_row + 1) * t_row / 2 + t_col] * v[col];
        }
        r[row] = sum;
    }
#ifdef DEBUG
    cout << "result1 is " << endl;
    for (int i = 0; i < Row; i++)
    {
        cout << r[i] << ' ';
    }
    cout << endl;
#endif // DEBUG
}
int main()
{
    init();
    t();
    triangular(vec, (float*)Triangular, Row, Col, res);
}