设n阶方阵A满足A[sup]2[/]=0,l为n阶单位矩阵,则()
A: |I-A|≠0,但|I+A|=0
B: |I-A|≠0,且|I+A|≠0
C: |I-A|=0,且|l+A|=0
D: |l-A|=0,但|l+A|≠0
A: |I-A|≠0,但|I+A|=0
B: |I-A|≠0,且|I+A|≠0
C: |I-A|=0,且|l+A|=0
D: |l-A|=0,但|l+A|≠0
举一反三
- Grammer G[]= ( {b} , {N , B} , N , {N→b│ bB , B→bN} ), The language described in this grammar is (). A: L(G[N])={bi│<br/>i ≥ 0} B: L(G[N])={b2i│<br/>i≥ 0} C: L(G[N])={b2i+1│<br/>i ≥ 0} D: L(G[N])={b2i+1│<br/>i ≥ 1}
- 【单选题】以下算法的时间复杂度() void matrimult(int a[M][N],int b[N][L],int c[M][L]) // { int i,j,k; for(i=0;i<M;i++) for(j=0;j<L;j++) c[i][j]=0; for(i=0;i<M;i++) for(j=0;j<L;j++) for(k=0;k<N;k++) c[i][j]+=a[i][k]*b[k][j]; } A. O(n*l) B. O(m*l) C. O(m*n) D. O(m*n*l)
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- 针对如下三个实现矩阵求和的不同函数:int a[N][N];int sumA( int a[N][N] ){ int i, j; int sum = 0; for ( i = 0; i < N; i++ ) for ( j = 0; j < N; j++ ) sum += a[i][j]; return sum;}int sumB( int a[N][N] ){ int i, j; int sum = 0; for ( j = 0; j < N; j++ ) for ( i = 0; i < N; i++ ) sum += a[i][j]; return sum;}int sumC( int a[N][N] ){ int i, j; int sum = 0; for ( j = 0; j < N; j+=2 ) for ( i = 0; i < N; i+=2 ) sum += ( a[i][j] + a[i+1][j] + a[i][j+1] + a[i+1][j+1] ); return sum;}当N足够大的时候,三个函数的运行时间t1、t2、t3符合下列哪种情况?()[/i][/i][/i][/i] A: t1 > t2 > t3 B: t3 > t1 > t2 C: t2 > t3 > t1 D: t3 > t2 > t1