Added 2 solutions & modified 1 solution

varunu28 · varunu28 · commit 1156d038ce08 · 2020-02-11T07:10:40.000-08:00
diff --git a/Easy/Student Attendance Record I.java b/Easy/Student Attendance Record I.java
@@ -1,18 +1,16 @@
 class Solution {
-    public boolean checkRecord(String s) {
-        int absCount = 0;
-        if (s.contains("LLL")) {
-            return false;
+  public boolean checkRecord(String s) {
+    int absentCount = 0;
+    for (int i = 0; i< s.length(); i++) {
+      if (s.charAt(i) == 'A') {
+        absentCount++;
+      }
+      else if (s.charAt(i) == 'L') {
+        if (i + 1 < s.length() && i + 2 < s.length() && s.charAt(i + 1) == 'L' && s.charAt(i + 2) == 'L') {
+          return false;
         }
-        
-        for (int i=0;i<s.length();i++) {
-            if (s.charAt(i) == 'A') {
-                absCount++;
-            }
-            if (absCount>1) {
-                return false;
-            } 
-        }
-        return true;
+      }
     }
+    return absentCount <= 1;
+  }
 }
diff --git a/Medium/Network Delay Time.java b/Medium/Network Delay Time.java
@@ -0,0 +1,49 @@
+class Solution {
+  public int networkDelayTime(int[][] times, int N, int K) {
+    Map<Integer, List<Connection>> map = new HashMap<>();
+    for (int[] time : times) {
+      map.computeIfAbsent(time[0], k -> new ArrayList<>()).add(new Connection(time[1], time[2]));
+    }
+    Map<Integer, Integer> dist = new HashMap<>();
+    for (int node = 1; node <= N; node++) {
+      dist.put(node, Integer.MAX_VALUE);
+    }
+    dist.put(K, 0);
+    boolean[] seen = new boolean[N + 1];
+    while (true) {
+      int candNode = -1;
+      int candDist = Integer.MAX_VALUE;
+      for (int i = 1; i <= N; ++i) {
+        if (!seen[i] && dist.get(i) < candDist) {
+          candDist = dist.get(i);
+          candNode = i;
+        }
+      }
+      if (candNode < 0) {
+        break;
+      }
+      seen[candNode] = true;
+      for (Connection con: map.getOrDefault(candNode, new ArrayList<>())) {
+        dist.put(con.val, Math.min(dist.get(con.val), dist.get(candNode) + con.time));
+      }
+    }
+    int ans = 0;
+    for (int cand: dist.values()) {
+      if (cand == Integer.MAX_VALUE) {
+        return -1;
+      }
+      ans = Math.max(ans, cand);
+    }
+    return ans;
+  }
+}
+
+class Connection {
+  int val;
+  int time;
+  
+  public Connection(int val, int time) {
+    this.val = val;
+    this.time = time;
+  }
+}
diff --git a/Medium/Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold.java b/Medium/Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold.java
@@ -0,0 +1,17 @@
+class Solution {
+  public int numOfSubarrays(int[] arr, int k, int threshold) {
+    int sum = 0;
+    int start = 0;
+    int count = 0;
+    for (int i = 0; i < arr.length; i++) {
+      sum += arr[i];
+      if (i - start + 1 == k) {
+        if ((double) sum / k >= threshold) {
+          count++;
+        }
+        sum -= arr[start++]; 
+      }
+    }
+    return count;
+  }
+}
