MakeTwoArraysEqualByReversingSubArrays.cpp

// Source : https://leetcode.com/problems/make-two-arrays-equal-by-reversing-sub-arrays/
// Author : Hao Chen
// Date   : 2020-10-02

/***************************************************************************************************** 
 *
 * Given two integer arrays of equal length target and arr.
 * 
 * In one step, you can select any non-empty sub-array of arr and reverse it. You are allowed to make 
 * any number of steps.
 * 
 * Return True if you can make arr equal to target, or False otherwise.
 * 
 * Example 1:
 * 
 * Input: target = [1,2,3,4], arr = [2,4,1,3]
 * Output: true
 * Explanation: You can follow the next steps to convert arr to target:
 * 1- Reverse sub-array [2,4,1], arr becomes [1,4,2,3]
 * 2- Reverse sub-array [4,2], arr becomes [1,2,4,3]
 * 3- Reverse sub-array [4,3], arr becomes [1,2,3,4]
 * There are multiple ways to convert arr to target, this is not the only way to do so.
 * 
 * Example 2:
 * 
 * Input: target = [7], arr = [7]
 * Output: true
 * Explanation: arr is equal to target without any reverses.
 * 
 * Example 3:
 * 
 * Input: target = [1,12], arr = [12,1]
 * Output: true
 * 
 * Example 4:
 * 
 * Input: target = [3,7,9], arr = [3,7,11]
 * Output: false
 * Explanation: arr doesn't have value 9 and it can never be converted to target.
 * 
 * Example 5:
 * 
 * Input: target = [1,1,1,1,1], arr = [1,1,1,1,1]
 * Output: true
 * 
 * Constraints:
 * 
 * 	target.length == arr.length
 * 	1 <= target.length <= 1000
 * 	1 <= target[i] <= 1000
 * 	1 <= arr[i] <= 1000
 ******************************************************************************************************/
class Solution {
public:
    // This problem could transfer to check two array has exactly same numbers
    bool canBeEqual(vector<int>& target, vector<int>& arr) {
       
       
        int len1 = target.size();
        int len2 = arr.size();
        if (len1 != len2) return false;
        if (len1 == 0) return true;
        
        unordered_map<int, int> stat;
        for (int i=0; i<len1; i++) {
            stat[target[i]]++;
            stat[arr[i]]--;
        }
        
        for (auto& s:stat) {
            if (s.second !=0 ) return false;
        }
        return true;
    }
    
};