Add java solution to LC775

Author: kate-melnykova

LC775-Global-and-Local-Inversions.java

@@ -0,0 +1,45 @@
+/*
+We have some permutation A of [0, 1, ..., N - 1], where N is the
+length of A.
+
+The number of (global) inversions is the number of i < j with
+0 <= i < j < N and A[i] > A[j].
+
+The number of local inversions is the number of i with 0 <= i < N
+and A[i] > A[i+1].
+
+Return true if and only if the number of global inversions is equal
+to the number of local inversions.
+
+Example 1:
+Input: A = [1,0,2]
+Output: true
+Explanation: There is 1 global inversion, and 1 local inversion.
+
+Example 2:
+Input: A = [1,2,0]
+Output: false
+Explanation: There are 2 global inversions, and 1 local inversion.
+Note:
+
+A will be a permutation of [0, 1, ..., A.length - 1].
+A will have length in range [1, 5000].
+The time limit for this problem has been reduced.
+*/
+
+class Solution {
+    public boolean isIdealPermutation(int[] A) {
+        int i = 0;
+        while (i + 1 < A.length){
+            if ((A[i] != i) && (A[i] != i+1)){
+                return false;
+            } else if ((A[i] == i+1) && (A[i+1] != i)){
+                return false;
+            } else if (A[i] == i+1){
+                i++;
+            }
+            i++;
+        }
+        return true;
+    }
+}