select m*m matrix from m*n matrix

spp
spp
@spp-8ADGRN • Oct 26, 2024

selection of m*m matrix from m*n matrix can be done in c(n,m) ways.

so can anyone sgeest me an algorithm or c/c++ programme to get all the possible selections.

thank you.

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  • pradeep_agrawal
    pradeep_agrawal

    @pradeep-agrawal-rhdX5z • Aug 20, 2009

    Could you please add more details on how the number of combinations can be c(n,m).

    As per me if you do simple selection (without crossing boundaries of matrix) then the number of combinations will be (n-m) and if you do complex selection (by crossing the boundaries of matrix) then the number of combination will be nxm.

    Crossing the boundaries of matrix mean considering the first element is adjacent to last element in a row and first element is adjacent to last element in a column.

    -Pradeep

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  • spp
    spp

    @spp-8ADGRN • Aug 21, 2009

    pradeep_agrawalCould you please add more details on how the number of combinations can be c(n,m).

    As per me if you do simple selection (without crossing boundaries of matrix) then the number of combinations will be (n-m) and if you do complex selection (by crossing the boundaries of matrix) then the number of combination will be nxm.

    Crossing the boundaries of matrix mean considering the first element is adjacent to last element in a row and first element is adjacent to last element in a column.

    -Pradeep

    suppose we take a 2*5 matrix ie
    1 5 7 8 9
    2 6 4 8 9
    then from this i have to select all 2*2 matrices
    so the possibilities are
    1 5 1 7 1 8 1 9 5 7 5 8 5 9 7 8 7 9 8 9
    2 6, 2 4, 2 8, 2 9, 6 4, 6 8, 6 9, 4 8, 4 9, 8 9
    so its c(5,2)=10 which is equal to the no of selection.

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  • Saandeep Sreerambatla
    Saandeep Sreerambatla

    @saandeep-sreerambatla-hWHU1M • Aug 25, 2009

    pradeep_agrawalCould you please add more details on how the number of combinations can be c(n,m).

    As per me if you do simple selection (without crossing boundaries of matrix) then the number of combinations will be (n-m) and if you do complex selection (by crossing the boundaries of matrix) then the number of combination will be nxm.

    Crossing the boundaries of matrix mean considering the first element is adjacent to last element in a row and first element is adjacent to last element in a column.

    -Pradeep


    I didnt get this Pradeep, How is it n-m and n*m can you give a small example ?

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