Задача 1

sm=[0]*m
for j in range(m):
  s=0
  for i in range(n):
    s+=a[i][j]
  sm[j]=s
mn_j=0
for j in range(1,m):
  if sm[j]<=sm[mn_j]:
    mn_j=j
for i in range(n):
  a[i][mn_j]=x[i]