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sub lower_bound1 { my @sorted; ... } return $min/2; }
0 1 2 3 4 min1 min2 0 0 1 (2) 3 1 1 ... lower_bound2: 19 = sum(min2)/2 - 15 + 1 + 1 (excluding col 0 and 4 for double rows, striking the maximum)