java: add «1395. Count Number of Teams»

Signed-off-by: Matej Focko <me@mfocko.xyz>

java/count-number-of-teams.java

@@ -0,0 +1,32 @@
+class Solution {
+  public int numTeams(int[] rating) {
+    int[][][] dp = new int[2][3][rating.length];
+
+    // base
+    for (int i = 0; i < rating.length; ++i) {
+      dp[0][0][i] = 1;
+      dp[1][0][i] = 1;
+    }
+
+    for (int count = 2; count <= 3; ++count) {
+      for (int i = 0; i < rating.length; ++i) {
+        for (int j = i + 1; j < rating.length; ++j) {
+          if (rating[i] < rating[j]) {
+            dp[0][count - 1][j] += dp[0][count - 2][i];
+          }
+
+          if (rating[i] > rating[j]) {
+            dp[1][count - 1][j] += dp[1][count - 2][i];
+          }
+        }
+      }
+    }
+
+    int teams = 0;
+    for (int i = 0; i < rating.length; ++i) {
+      teams += dp[0][2][i] + dp[1][2][i];
+    }
+
+    return teams;
+  }
+}