Rotate image challenge

#1

hey in this code
int main(int argc, char* argv[])
what do the bracket elements signify? i couldnt understand this.
for(int i=0;i<n;i++) {
for(int j=i;j<m;j++) {
swap(array[i][j],array[j][i]);
}
}

for(int i=0;i<n;i++) {
    int lo = 0;
    int hi = n-1;
    while(lo<=hi) {
        swap(array[lo][i], array[hi][i]);
        lo++;
        hi--;
    }
}

also in the above code what is happening??

#2

@mkidwai74 swap (array[i][j] ,array[j][i]) interchange the value stored at i,j position with j,i position.

for input:
4
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16

in the given code first we are swapping element at ith row and jth column with element at jth row and ith column.

it will give us output:
1 5 9 13
2 6 10 14
3 7 11 15
4 8 12 16

after that we are swapping lo’th row and ith column with hi’th row and ith column
to get the desired answer