add FeelSafe solution

Author: jakovmitrovski

medium300/FeelSafe.java

@@ -0,0 +1,62 @@
+package medium300;
+
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class FeelSafe {
+
+    int[][] dp = new int[1001][1001];
+
+    class Canal {
+        int x1, y1, x2, y2;
+
+        public Canal(int x1, int y1, int x2, int y2) {
+            this.x1 = x1;
+            this.y1 = y1;
+            this.x2 = x2;
+            this.y2 = y2;
+        }
+
+        int getArea() {
+            return (y2 - y1) * (x2 - x1);
+        }
+    }
+
+    boolean inside(Canal c1, Canal c2) {
+        return c2.x1 > c1.x1 && c2.y1 > c1.y1 && c2.x2 < c1.x2 && c2.y2 < c1.y2;
+    }
+
+    public int maximumCanalCount(int[] x1, int[] y1, int[] x2, int[] y2) {
+
+        Canal[] c = new Canal[x1.length];
+
+        for (int i = 0; i < x1.length; i++)
+            c[i] = new Canal(Math.min(x1[i], x2[i]),
+                    Math.min(y1[i], y2[i]),
+                    Math.max(x1[i], x2[i]),
+                    Math.max(y1[i], y2[i]));
+
+        List<Canal> list = Arrays.stream(c).sorted(Comparator.comparing(Canal::getArea)).collect(Collectors.toList());
+
+        int[] dp = new int[51];
+        int rez = 0;
+        for (int i = 0; i < x1.length; i++)
+            for (int j = 0; j < i; j++) {
+                if (inside(list.get(i), list.get(j))) {
+                    dp[i] = Math.max(dp[i], dp[j] + 1);
+                    rez = Math.max(rez, dp[i]);
+                }
+            }
+
+        return rez + 1;
+    }
+
+    public static void main(String[] args) {
+        FeelSafe f = new FeelSafe();
+        System.out.println(f.maximumCanalCount(new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 },
+                new int[] { 20, 19, 18, 17, 16, 15, 14, 13, 12, 11 },
+                new int[] { 20, 19, 18, 17, 16, 15, 14, 13, 12, 11 }, new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }));
+    }
+}