Each number tells how many children standing ahead of that child in the line are taller than the child. Nothing about actual heights is revealed — only a comparison.
In the first picture the seven children call out, from the left:
Read them one by one:
- The first child has nobody ahead, so the number must be 0.
- The second child has one taller child ahead, so 1.
- The third child is the tallest of all, so no one ahead is taller — 0.
- The last child has only the tallest child and one more taller child ahead — 1.