Luogu2455 [SDOI2006]线性方程组（高斯消元）

模板特殊情况没exit(0) $\longrightarrow$60 了一下午

//#include <iostream>

#include <cstdio>

#include <cstring>

#include <algorithm>

#include <cmath>

#define R(a,b,c) for(register int  a = (b); a <= (c); ++ a)

#define nR(a,b,c) for(register int  a = (b); a >= (c); -- a)

#define Max(a,b) ((a) > (b) ? (a) : (b))

#define Min(a,b) ((a) < (b) ? (a) : (b))

#define Fill(a,b) memset(a, b, sizeof(a))

#define Abs(a) ((a) < 0 ? -(a) : (a))

#define Swap(a,b) a^=b^=a^=b

#define ll long long

#define ON_DEBUG

#ifdef ON_DEBUG

#define D_e_Line printf("\n\n----------\n\n")

#define D_e(x)  cout << #x << " = " << x << endl

#define Pause() system("pause")

#define FileOpen() freopen("in.txt","r",stdin);

#else

#define D_e_Line ;

#define D_e(x)  ;

#define Pause() ;

#define FileOpen() ;

#endif

struct ios{

    template<typename ATP>ios& operator >> (ATP &x){

        x = 0; int f = 1; char c;

        for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-')  f = -1;

        while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();

        x*= f;

        return *this;

    }

}io;

using namespace std;

const int N = 107;

const double eps = 1e-8;

int n;

double a[N][N], ans[N];

inline double fabs(double a){

	return a < 0 ? -a : a;

}

inline void Gauss(){

	R(i,1,n){

		int r = i;

		R(j,i + 1,n)

			if(fabs(a[j][i]) > fabs(a[r][i]))

				r = j;

		if(i != r) swap(a[i], a[r]);

		if(fabs(a[i][i]) > eps){

			R(j,1,n){

				if(i == j) continue;

				double s = a[j][i] / a[i][i];

				R(k,1,n + 1)

					a[j][k] -= s * a[i][k];

			}

		}

	}

	int flagNo = 0, flagInf = 0;

	R(i,1,n){

		int tot = 0;

		R(j,1,n + 1){

			if(fabs(a[i][j]) < eps)

				++tot;

			else

				break;

		}

		if(tot == n + 1) flagInf = 1;

		else if(tot == n && fabs(a[i][n + 1]) > eps) flagNo = 1;

	}

	if(flagNo == 1){ printf("-1"); exit(0);}

	if(flagInf == 1){ printf("0"); exit(0);}

	nR(i,n,1){

		ans[i] = a[i][n + 1] / a[i][i];

		nR(j,i - 1,1){

			a[j][n + 1] -= a[j][i] * ans[i];

		}

	}

}

int main(){

	io >> n;

	R(i,1,n){

		R(j,1,n + 1){

			scanf("%lf", &a[i][j]);

		}

	}

	Gauss();

	R(i,1,n){

//		if(fabs(ans[i]) < eps)

//			printf("x%d=0\n", i);

//		else

			printf("x%d=%.2lf\n", i, ans[i]);

	}

	return 0;

}

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Luogu2455 [SDOI2006]线性方程组（高斯消元）

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Luogu2455 [SDOI2006]线性方程组 （高斯消元）

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Luogu2455 [SDOI2006]线性方程组（高斯消元）