【模板】高斯消元法
洛谷1583
1 #include<cstdio> 2 #include<algorithm> 3 using namespace std; 4 const int maxn=1000; 5 int n,x; 6 double a[maxn][maxn]; 7 inline void read(int &k){ 8 k=0; int f=1; char c=getchar(); 9 while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar(); 10 while('0'<=c&&c<='9')k=k*10+c-'0',c=getchar(); 11 k*=f; 12 } 13 void swap_a(int x,int y){for (int i=1;i<=n+1;i++) swap(a[x][i],a[y][i]);} 14 bool Gauss(){ 15 int now=1; 16 while(now<=n){ 17 if (a[now][now]==0){ 18 for (int i=now+1;i<=n;i++) if(a[i][now]!=0) {swap_a(i,now); break;} 19 if (a[now][now]==0) return puts("No Solution"),0; 20 } 21 double tmp=a[now][now]; 22 for (int i=1;i<=n+1;i++) a[now][i]=a[now][i]/tmp; 23 for (int i=1;i<=n;i++){ 24 if (i==now) continue; double tmp=a[i][now]; 25 for (int j=1;j<=n+1;j++) a[i][j]-=a[now][j]*tmp; 26 } 27 now++; 28 } 29 return 1; 30 } 31 int main(){ 32 read(n); 33 for (int i=1;i<=n;i++) 34 for (int j=1;j<=n+1;j++) read(x),a[i][j]=x; 35 if (Gauss()) for (int i=1;i<=n;i++) printf("%.2f\n",a[i][n+1]); printf("\n"); 36 return 0; 37 }
