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if(root==null)
return 0;
int left=minDepth(root.left);
int right=minDepth(root.right);
if(left==0 || right==0)
{
return 1+left+right;
}
else
{
return 1+Math.min(left,right);
}
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if(root==null)
return 0;
int left=maxDepth(root.left);
int right=maxDepth(root.right);
if(left==0 || right==0)
{
return 1+left+right;
}
else
{
return 1+Math.max(left,right);
}