Fix: UniformIntGenerator range error (#7143)

* Fix: UniformIntGenerator range error

* Fix the UniformIntGenerator function description

* Fix: change the validation check conform to std::uniform_int_distribution

* apply style

---------

Co-authored-by: Benjamin Ummenhofer <benjamin.ummenhofer@intel.com>

cpp/open3d/utility/Random.h

@@ -43,7 +43,7 @@ std::mutex* GetMutex();
 /// This function is automatically protected by the global random mutex.
 uint32_t RandUint32();
 
-/// Generate uniformly distributed random integers in [low, high).
+/// Generate uniformly distributed random integers in [low, high].
 /// This class is globally seeded by utility::random::Seed().
 /// This class is a wrapper around std::uniform_int_distribution.
 ///
@@ -54,7 +54,7 @@ uint32_t RandUint32();
 /// // Globally seed Open3D. This will affect all random functions.
 /// utility::random::Seed(0);
 ///
-/// // Generate a random int in [0, 100).
+/// // Generate a random int in [0, 100].
 /// utility::random::UniformIntGenerator<int> gen(0, 100);
 /// for (size_t i = 0; i < 10; i++) {
 ///     std::cout << gen() << std::endl;
@@ -64,17 +64,18 @@ template <typename T>
 class UniformIntGenerator {
 public:
     /// Generate uniformly distributed random integer from
-    /// [low, low + 1, ... high - 1].
+    /// [low, low + 1, ... high].
     ///
     /// \param low The lower bound (inclusive).
-    /// \param high The upper bound (exclusive). \p high must be > \p low.
+    /// \param high The upper bound (inclusive). \p high must be >= \p low.
     UniformIntGenerator(const T low, const T high) : distribution_(low, high) {
         if (low < 0) {
             utility::LogError("low must be > 0, but got {}.", low);
         }
-        if (low >= high) {
-            utility::LogError("low must be < high, but got low={} and high={}.",
-                              low, high);
+        if (low > high) {
+            utility::LogError(
+                    "low must be <= high, but got low={} and high={}.", low,
+                    high);
         }
     }