找出3个数中不为-1的最小数

假设有3个数，它们的取值都可能为-1，现在要求找出其中不为-1的最小的数。本来我一开始的想法是利用8次if判断，知道我看到一位老师如下去实现。

int taaIndex = findStopCodon(dna, startIndex, "TAA");
int tagIndex = findStopCodon(dna, startIndex, "TAG");
int tgaIndex = findStopCodon(dna, startIndex, "TGA");
        
int minIndex = 0;
if (taaIndex == -1 || 
         (tgaIndex != -1 && tgaIndex < taaIndex)) {
               minIndex = tgaIndex;
}
else {
      minIndex = taaIndex;
}
        
if (minIndex == -1 ||
         (tagIndex != -1 && tagIndex < minIndex)) {
                minIndex = tagIndex;
}