doubleBasePalindromes(1000)
应该返回1772。
testString: assert(doubleBasePalindromes(1000) == 1772);
- text: doubleBasePalindromes(50000)
应该返回105795。
testString: assert(doubleBasePalindromes(50000) == 105795);
- text: doubleBasePalindromes(500000)
应该返回286602。
testString: assert(doubleBasePalindromes(500000) == 286602);
- text: doubleBasePalindromes(1000000)
应该返回872187。
testString: assert(doubleBasePalindromes(1000000) == 872187);
```