洛谷 P3389 【模板】高斯消元法

题意简述

给定一个线性方程组，对其求解

题解思路

高斯消元法

代码

#include <cstdio>
using namespace std;
const double eps = 1e-8;
int n, mini;
double a[1000][1000];
double _abs(double x) {return x < 0 ? -x : x; }
void _swap(double &x, double &y) {double t = x; x = y; y = t; }
int main()
{
    scanf("%d", &n);
    for (register int i = 1; i <= n; ++i)
        for (register int j = 1; j <= n + 1; ++j)
            scanf("%lf", &a[i][j]);
    for (register int i = 1; i <= n; ++i)
    {
        mini = i;
        for (register int j = i + 1; j <= n; ++j)
            if (_abs(a[j][i]) > _abs(a[mini][i]))
                mini = j;
        for (register int j = 1; j <= n + 1; ++j) _swap(a[i][j], a[mini][j]);
        if (_abs(a[i][i]) <= eps)
        {
            puts("No Solution");
            return 0;
        }
        for (register int j = n + 1; j >= i; --j) a[i][j] /= a[i][i];
        for (register int j = 1; j <= n; ++j)
            if (i ^ j)
                for (register int k = n + 1; k >= i; --k)
                    a[j][k] -= a[i][k] * a[j][i];
    }
    for (register int i = 1; i <= n; ++i) printf("%.2lf\n", a[i][n + 1]);
}

洛谷 P3389 【模板】高斯消元法

原文：https://www.cnblogs.com/xuyixuan/p/9663560.html