高斯消元的優化，為了避免分母過小造成的誤差，在每次選取基準數的時候在每列中選擇最大的那個並於該行做初等行變換，該**的時間複雜度為 o(n
4)o(n^4)
o(n4
)
/*
wang_zibi 列消元 */
#include
#define int long long
using
namespace std;
typedef pair<
int,
int> pii;
const
int n =
1e4+10;
double a[n]
[n];
int n, m;
const
double inf =
0x3f3f3f3f
;void
test()
}void
deal
(int x)}if
(flag.second!=
-inf)
for(
int i =
0; i < m; i++
)swap
(a[flag.second]
[i], a[x]
[i]);}
void
gauss()
}}for(
int j =
2; j >=
0; j--
) a[j]
[j]= a[j][3
]/ a[j]
[j];}}
void
solve()
signed
main()
class
gauss
:def
__init__
(self, m, nn, mm)
: self.matrix = m
self.n = nn
self.m = mm
def__deal
(self, t)
: x =
-9999999.0
y =none
for i in
range
(t+1
,self.n):if
(self.matrix[i]
[t]> x)
: x = self.matrix[i]
[t] y=i
for i in
range(0
,self.m)
: temp = self.matrix[t]
[i] self.matrix[t]
[i]= self.matrix[y]
[i] self.matrix[y]
[i]=temp
defsolve
(self)
:for k in
range(0
, self.n)
: self.__deal(k)
for i in
range
(k +
1, self.n)
: t = self.matrix[i]
[k]/ self.matrix[k]
[k]for j in
range(0
, self.m)
: self.matrix[i]
[j]-= self.matrix[k]
[j]* t
for j in
range
(self.n -1,
-1,-
1):for k in
range
(j +
1, self.n)
: self.matrix[j]
[self.n]
= self.matrix[j]
[self.n]
- self.matrix[j]
[k]* self.matrix[k]
[k] self.matrix[j]
[j]= self.matrix[j]
[self.n]
/ self.matrix[j]
[j]for i in
range(0
, self.m -1)
:print
(self.matrix[i]
[i], end=
' ')
defmain()
: n,m=
map(
int,
input()
.split())
line =[[
0]* m]
* n for i in
range
(n):
line[i]
=input()
.split(
" ")
line[i]
=list
(map
(int
,line[i]))
g = gauss(line,n,m)
g.solve(
)main(
)
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