vector - Transform an upper triangular matrix into a full matrix C++ -

how code can transform upper triangular matrix total matrix. matrix in vector, not in bidimensional array...

so array

[ 1 2 3 4 0 5 6 7 0 0 8 9 0 0 0 10 ]

would become array like:

[ 1 2 3 4 2 5 6 7 3 6 8 9 4 7 9 10 ]

could provide ideas, thinking in applying kind of module or something...

there 1 restriction, i not using bidimensional arrays usng vector, unidimensional array

first, must understand fundemtnal nature of reflected matrix. i, j, next assertion true:

m[i][j] ≡ m[j][i]

so, need algorithm create true. may suggest:

for(int = 0; < height; ++i) for(int j = 0; j < i; ++j) m[i][j] = m[j][i];

note status of 2nd loop. ensuring j less i, restrict our activity bottom-left triangle.

next, must understand how have implemented two-dimensional matrix in one-dimensional array. appears have established identity:

m[i][j] ≡ v[i*width+j]

substituting, have:

for(int = 0; < height; ++i) for(int j = 0; j < i; ++j) v[i*width+j] = v[j*width+i];

c++ vector matrix

JC