Problem: p02720
Buggy submission (PyPy3 (2.4.0), verdict: Wrong Answer):
    
def make_tree(G,keta,count):
    if keta==1:
        num =[]
        for i in range(1,10):
            count+=1
            if count ==k:
                print(i)
                exit()
            else:
                num.append(i)
        G.append(num)
        make_tree(G,2,count)
    else:
        print(G)
        num_list = G[keta-2]
        num_lis =[]
        for num in num_list:
            num_str = str(num)
            num_e = int(num_str[-1])
            if num_e == 0:
                count +=1
                if count == k :
                    print(int(num_str + "0"))
                    exit()
                num_lis.append(int((num_str)+"0"))
                count+=1
                if count == k :
                    print(int(num_str + "1"))
                    exit()
                num_lis.append(int((num_str)+"1"))
            elif num_e == 9:
                count +=1
                if count == k :
                    print(int(num_str + "8"))
                    exit()
                num_lis.append(int((num_str)+"8"))
                count+=1
                if count == k :
                    print(int(num_str + "8"))
                    exit()
                num_lis.append(int((num_str)+"9"))
            else:
                count +=1
                if count == k :
                    print(int(num_str + str(num_e-1)))
                    exit()
                num_lis.append(int(num_str + str(num_e-1)))
                count+=1
                if count == k :
                    print(int(num_str + str(num_e)))
                    exit()
                num_lis.append(int(num_str + str(num_e)))
                count+=1
                if count == k :
                    print(int(num_str + str(num_e+1)))
                    exit()
                num_lis.append(int(num_str + str(num_e+1)))
        G.append(num_lis)

        make_tree(G,keta+1,count)


k = int(input())
G=[]
make_tree(G,1,0)

Failing test case input:
333

Expected output:
10100


Actual output:
[[1, 2, 3, 4, 5, 6, 7, 8, 9]]
[[1, 2, 3, 4, 5, 6, 7, 8, 9], [10, 11, 12, 21, 22, 23, 32, 33, 34, 43, 44, 45, 54, 55, 56, 65, 66, 67, 76, 77, 78, 87, 88, 89, 98, 99]]
[[1, 2, 3, 4, 5, 6, 7, 8, 9], [10, 11, 12, 21, 22, 23, 32, 33, 34, 43, 44, 45, 54, 55, 56, 65, 66, 67, 76, 77, 78, 87, 88, 89, 98, 99], [100, 101, 110, 111, 112, 121, 122, 123, 210, 211, 212, 221, 222, 223, 232, 233, 234, 321, 322, 323, 332, 333, 334, 343, 344, 345, 432, 433, 434, 443, 444, 445, 454, 455, 456, 543, 544, 545, 554, 555, 556, 565, 566, 567, 654, 655, 656, 665, 666, 667, 676, 677, 678, 765, 766, 767, 776, 777, 778, 787, 788, 789, 876, 877, 878, 887, 888, 889, 898, 899, 987, 988, 989, 998, 999]]
[[1, 2, 3, 4, 5, 6, 7, 8, 9], [10, 11, 12, 21, 22, 23, 32, 33, 34, 43, 44, 45, 54, 55, 56, 65, 66, 67, 76, 77, 78, 87, 88, 89, 98, 99], [100, 101, 110, 111, 112, 121, 122, 123, 210, 211, 212, 221, 222, 223, 232, 233, 234, 321, 322, 323, 332, 333, 334, 343, 344, 345, 432, 433, 434, 443, 444, 445, 454, 455, 456, 543, 544, 545, 554, 555, 556, 565, 566, 567, 654, 655, 656, 665, 666, 667, 676, 677, 678, 765, 766, 767, 776, 777, 778, 787, 788, 789, 876, 877, 878, 887, 888, 889, 898, 899, 987, 988, 989, 998, 999], [1000, 1001, 1010, 1011, 1012, 1100, 1101, 1110, 1111, 1112, 1121, 1122, 1123, 1210, 1211, 1212, 1221, 1222, 1223, 1232, 1233, 1234, 2100, 2101, 2110, 2111, 2112, 2121, 2122, 2123, 2210, 2211, 2212, 2221, 2222, 2223, 2232, 2233, 2234, 2321, 2322, 2323, 2332, 2333, 2334, 2343, 2344, 2345, 3210, 3211, 3212, 3221, 3222, 3223, 3232, 3233, 3234, 3321, 3322, 3323, 3332, 3333, 3334, 3343, 3344, 3345, 3432, 3433, 3434, 3443, 3444, 3445, 3454, 3455, 3456, 4321, 4322, 4323, 4332, 4333, 4334, 4343, 4344, 4345, 4432, 4433, 4434, 4443, 4444, 4445, 4454, 4455, 4456, 4543, 4544, 4545, 4554, 4555, 4556, 4565, 4566, 4567, 5432, 5433, 5434, 5443, 5444, 5445, 5454, 5455, 5456, 5543, 5544, 5545, 5554, 5555, 5556, 5565, 5566, 5567, 5654, 5655, 5656, 5665, 5666, 5667, 5676, 5677, 5678, 6543, 6544, 6545, 6554, 6555, 6556, 6565, 6566, 6567, 6654, 6655, 6656, 6665, 6666, 6667, 6676, 6677, 6678, 6765, 6766, 6767, 6776, 6777, 6778, 6787, 6788, 6789, 7654, 7655, 7656, 7665, 7666, 7667, 7676, 7677, 7678, 7765, 7766, 7767, 7776, 7777, 7778, 7787, 7788, 7789, 7876, 7877, 7878, 7887, 7888, 7889, 7898, 7899, 8765, 8766, 8767, 8776, 8777, 8778, 8787, 8788, 8789, 8876, 8877, 8878, 8887, 8888, 8889, 8898, 8899, 8987, 8988, 8989, 8998, 8999, 9876, 9877, 9878, 9887, 9888, 9889, 9898, 9899, 9987, 9988, 9989, 9998, 9999]]
10100


Fixed submission (verdict: Accepted):
def make_tree(G,keta,count):
    if keta==1:
        num =[]
        for i in range(1,10):
            count+=1
            if count ==k:
                print(i)
                exit()
            else:
                num.append(i)
        G.append(num)
        make_tree(G,2,count)
    else:
        
        num_list = G[keta-2]
        num_lis =[]
        for num in num_list:
            num_str = str(num)
            num_e = int(num_str[-1])
            if num_e == 0:
                count +=1
                if count == k :
                    print(int(num_str + "0"))
                    exit()
                num_lis.append(int((num_str)+"0"))
                count+=1
                if count == k :
                    print(int(num_str + "1"))
                    exit()
                num_lis.append(int((num_str)+"1"))
            elif num_e == 9:
                count +=1
                if count == k :
                    print(int(num_str + "8"))
                    exit()
                num_lis.append(int((num_str)+"8"))
                count+=1
                if count == k :
                    print(int(num_str + "9"))
                    exit()
                num_lis.append(int((num_str)+"9"))
            else:
                count +=1
                if count == k :
                    print(int(num_str + str(num_e-1)))
                    exit()
                num_lis.append(int(num_str + str(num_e-1)))
                count+=1
                if count == k :
                    print(int(num_str + str(num_e)))
                    exit()
                num_lis.append(int(num_str + str(num_e)))
                count+=1
                if count == k :
                    print(int(num_str + str(num_e+1)))
                    exit()
                num_lis.append(int(num_str + str(num_e+1)))
        G.append(num_lis)

        make_tree(G,keta+1,count)


k = int(input())
G=[]
make_tree(G,1,0)