Make737Hard | Topcoder Archive

Problem Statement

Given a string S, a 737-triple in S is a triple (i,j,k) such that:

i, j, k are valid indices into S such that i < j < k
S[i] = '7', S[j] = '3', and S[k] = '7'.

You are given an int X. Your task is to generate and return any string S such that:

The length of S is between 1 and 373, inclusive.
The string S contains only characters '3' and '7'.
The number of 737-triples in S is exactly X.

You may assume that for the given constraints a solution always exists.

Definition

Class:: Make737Hard
Method:: make
Parameters:: int
Returns:: String
Method signature:: String make(int X)
(be sure your method is public)

Constraints

X will be between 0 and 1,737,373, inclusive.

Examples

```
1
```
```
Returns: "737"
```
```
8
```
```
Returns: "773377"
```
```
0
```
```
Returns: "777333"
```
```
4
```
```
Returns: "73737"
```

This problem statement is the exclusive and proprietary property of Topcoder, Inc. Any unauthorized use or reproduction of this information without the prior written consent of Topcoder, Inc. is strictly prohibited. (c)2024, Topcoder, Inc. All rights reserved.