# Generate a sequence with the given operations

Given a string which contains only (increase) and (decrease). The task is to return any permutation of integers **[0, 1, …, N]** where **N ≤ Length of S** such that for all **i = 0, …, N-1**:

- If S[i] == “D”, then A[i] > A[i+1]
- If S[i] == “I”, then A[i] < A[i+1].

**Note** that output must contain distinct elements.

**Examples:**

Input:S = “DDI”

Output:[3, 2, 0, 1]

Input:S = “IDID”

Output:[0, 4, 1, 3, 2]

**Approach:** If **S[0] == “I”**, then choose as the first element. Similarly, if **S[0] == “D”**, then choose as the first element. Now for every operation, choose the next maximum element which hasn’t been chosen before from the range **[0, N]** and for the operation, choose the next minimum.

Below is the implementation of the above approach:

## C++

`//C++ Implementation of above approach ` `#include<bits/stdc++.h> ` `using` `namespace` `std; ` ` ` `// function to find minimum required permutation ` ` ` `void` `StringMatch(string s) ` ` ` `{ ` ` ` `int` `lo=0, hi = s.length(), len=s.length(); ` ` ` `vector<` `int` `> ans; ` ` ` `for` `(` `int` `x=0;x<len;x++) ` ` ` `{ ` ` ` `if` `(s[x] == ` `'I'` `) ` ` ` `{ ` ` ` `ans.push_back(lo) ; ` ` ` `lo += 1; ` ` ` `} ` ` ` `else` ` ` `{ ` ` ` `ans.push_back(hi) ; ` ` ` `hi -= 1; ` ` ` `} ` ` ` `} ` ` ` `ans.push_back(lo) ; ` ` ` `cout<<` `"["` `; ` ` ` `for` `(` `int` `i=0;i<ans.size();i++) ` ` ` `{ ` ` ` `cout<<ans[i]; ` ` ` `if` `(i!=ans.size()-1) ` ` ` `cout<<` `","` `; ` ` ` `} ` ` ` `cout<<` `"]"` `; ` `} ` `// Driver code ` `int` `main() ` `{ ` `string S = ` `"IDID"` `; ` `StringMatch(S); ` `return` `0; ` `} ` `//contributed by Arnab Kundu ` |

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## Python

`# Python Implementation of above approach ` ` ` `# function to find minimum required permutation ` `def` `StringMatch(S): ` ` ` `lo, hi ` `=` `0` `, ` `len` `(S) ` ` ` `ans ` `=` `[] ` ` ` `for` `x ` `in` `S: ` ` ` `if` `x ` `=` `=` `'I'` `: ` ` ` `ans.append(lo) ` ` ` `lo ` `+` `=` `1` ` ` `else` `: ` ` ` `ans.append(hi) ` ` ` `hi ` `-` `=` `1` ` ` ` ` `return` `ans ` `+` `[lo] ` ` ` `# Driver code ` `S ` `=` `"IDID"` `print` `(StringMatch(S)) ` |

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**Output:**

[0, 4, 1, 3, 2]

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