回文是指一段数字或者文本，正着读和倒着读都是相同的，例如2002，110011都是回文数字。 请编写一个函数，接收一个数字参数num，返回最靠近num的一个回文数字，数值比num小一点或者大一点都可以。 如果存在多个可能的值，则返回其中较大的数字；如果数字本身就是回文数字，直接返回自身。 个位数字（0～9）不被视为回文数字。
【示例】
输入：1029
输出：1001
解释：数字1029附近的回文数字分别有1001和1111，但是1001更接近1029，因此返回1001。
题目难度：中等
题目来源：CodeWars-Numerical Palindrome #4
def solution(num: int)-> int:
# your code here
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221
def solution(num: int)-> int:
# your code here
if num > 0 and num <= 10:
return 11
if str(num) == str(num)[::-1]:
return num
# 寻找小于num的回文数字
res_list1 = []
res_list2 = []
close_minnum = None
close_maxnum = None
diff_num = None
for i in range(11,num):
if str(i) == str(i)[::-1]:
res_list1.append(i)
# 取小于num的回文数字中最大的一个数，并计算差值
close_minnum = max(res_list1)
diff_num = num - close_minnum
# 寻找num + 差值之间是否还有回文，有则返回其最小值，没有则返回close_minnum
for i in range(num+1,num+diff_num+1):
if str(i) == str(i)[::-1]:
res_list2.append(i)
if res_list2 == []:
return close_minnum
else:
close_maxnum = min(res_list2)
return close_maxnum
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221
def solution（n：int）：
if n<11:
return 11
I=0
while n>10:
If str(n-I) ==str(n-I)[::-1]:
return n-I
elif str(n+1)==str(n+1)[::-1]:
return n+1
I+=1
def solution(num: int)-> int:
# your code here
if num < 10 :
return 11
else :
num1 = num
num2 = num
result = []
while not result:
if str(num) == str(num)[::-1] :
result.append(num)
if str(num1) == str(num1)[::-1] :
result.append(num1)
if str(num2) == str(num2)[::-1] :
result.append(num2)
if result:
return sorted(result)[-1]
num1 += 1
num2 -= 1
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221
def solution(num: int)-> int:
# your code here
num = str(num)
if num == num[::-1] and int(num) > 10:
return int(num)
i = int(num) + 1
while str(i) != str(i)[::-1] or i < 10:
i = i + 1
j = int(num) - 1
while str(j) != str(j)[::-1]:
j = j - 1
if j < 10:
break
if i-int(num) > int(num)-j and j > 10:
return j
else:
return i
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221
def solution(num: int) -> int:
# your code here
if num < 10:
return 11
elif str(num) == str(num)[::-1]:
return num
else:
result = []
n = 1
while n:
if str(num + n) == str(num + n)[::-1]:
result.append(num + n)
if str(num - n) == str(num - n)[::-1]:
result.append(num - n)
if result:
return sorted(result)[-1]
n += 1
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221
def solution(num: int) -> int:
if num <= 16:
return 11
add = reduce = num
while True:
if str(add) == str(add)[::-1]:
return add
if reduce > 9 and str(reduce) == str(reduce)[::-1]:
return reduce
add += 1
reduce -= 1
def solution(num: int) -> int:
if 0 < num <= 10:
return 11
elif str(num) == str(num)[::-1]:
return num
else:
close_num1 = max([n for n in range(11, num) if str(n) == str(n)[::-1]])
dif_num = num - close_num1
if [n for n in range(num, num + dif_num + 1) if str(n) == str(n)[::-1]] == []:
return close_num1
else:
return min([n for n in range(num, num + dif_num + 1) if str(n) == str(n)[::-1]])
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221
# Daily_20220411
def solution(num: int)-> int:
# your code here
if isinstance(num, int):
if 0 < num <= 10:
return 11
elif str(num) == str(num)[::-1]:
return num
else:
max_result = []
min_result = []
for i in range(11, num+1):
if str(i) == str(i)[::-1]:
max_result.append(i)
max_num = max(max_result)
diff_max_num = num - max_num
for i in range(num+1, diff_max_num+(num+1)):
if str(i) == str(i)[::-1]:
min_result.append(i)
if not min_result or min(min_result) - num > diff_max_num:
return max_num
else:
return min(min_result)
else:
print('input error.')
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221
def solution(num: int)-> int:
maybe_value=[]
count = 0
while True:
if len(str(num-count)) >1 and str(num-count) == str(num-count)[::-1]:
maybe_value.append(num-count)
if len(str(num+count)) >1 and str(num+count) == str(num+count)[::-1]:
maybe_value.append(num+count)
if maybe_value:
return sorted(maybe_value)[-1]
count = count +1
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertAll;
import static org.junit.jupiter.api.Assertions.assertEquals;
public class Palindrome {
@Test
void demoTest() {
assertAll(
()-> assertEquals(palindrome(8),11),
()-> assertEquals(palindrome(281),282),
()-> assertEquals(palindrome(1029),1001),
()-> assertEquals(palindrome(10293456),10288201),
()-> assertEquals(palindrome(1221),1221)
);
}
public int palindrome(int number) {
String numberOf = number + "";
String reverse = new StringBuilder(numberOf).reverse().toString();
int reversed;
if (number > 0 && number < 10) {
return 11;
} else if (reverse.equals(numberOf)) {
return number;
} else {
int maxReverse =0;
int minReverse =0;
for (int i = number;i>10;i--){
String ans1 = i + "";
String reverse1= new StringBuffer(ans1).reverse().toString();
if (ans1.equals(reverse1)){
minReverse=i;
break;
}
}
for (int s = number;;s++){
String ans2 = s + "";
String reverse2 = new StringBuffer(ans2).reverse().toString();
if (ans2.equals(reverse2)){
maxReverse =s;
break;
}
}
if (maxReverse-number>number-minReverse){
reversed=minReverse;
}else {
reversed=maxReverse;
}
return reversed;
}
}
}
def solution(num: int) -> int:
if num <= 11:
return 11
step = 0
while True:
left = str(num - step)
right = str(num + step)
if right == right[::-1]:
return int(right)
if left == left[::-1] and int(left) > 9:
return int(left)
step += 1 # 齐步走~
def fun(num: str) -> bool:
if num == ''.join(reversed(num)) and len(num) > 1:
return True
else:
return False
def solution(num: int) -> int:
if num < 10:
return 11
elif fun(str(num)):
return num
else:
num_max = num + 1
num_min = num - 1
while True:
if fun(str(num_max)):
return num_max
if fun(str(num_min)):
return num_min
num_max += 1
num_min -= 1
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221
def solution(num: int)-> int:
if num<10:
return 11
else:
min_num=0
for i in range(num,10,-1):
if str(i)==str(i)[::-1]:
min_num=i
break
max_num=num
while True:
max_num+=1
if str(max_num)==str(max_num)[::-1]:
break
num_list=[min_num,max_num]
if num-num_list[0]>max_num-num:
return max_num
elif num-num_list[0]<max_num-num:
return min_num
assert solution(8) == 11
assert solution(281) == 282
assert solution(1029) == 1001
assert solution(1221) == 1221