Create: 2251-number-of-flowers-in-full-bloom.java

Author: sarthak-2305

java/2251-number-of-flowers-in-full-bloom.java

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+class Solution {
+    public int[] fullBloomFlowers(int[][] flowers, int[] people) {
+        //separate the start and end times and sort them
+        int[] start = new int[flowers.length];
+        int[] end = new int[flowers.length];
+
+        for (int i = 0; i<flowers.length; i++) {
+            start[i] = flowers[i][0];
+            end[i] = flowers[i][1];
+        }
+        Arrays.sort(start);
+        Arrays.sort(end);
+
+        int[] result = new int[people.length];
+
+        //use binary search and find the number of flowers blooming
+        for (int i = 0; i<people.length; i++) {
+            int bloom = blooming(start, people[i]);
+            int notBloom = notBlooming(end, people[i]);
+            result[i] = bloom - notBloom;
+        }
+        
+        return result;
+    }
+
+    //find upper bound of flowers blooming
+    public int blooming(int[] start, int index) {
+        int left = 0; 
+        int right = start.length;
+
+        while (left<right) {
+            int mid = left + (right-left)/2;
+            if (start[mid] <= index) {
+                left = mid + 1;
+            } else {
+                right = mid;
+            }
+        }
+        return right;
+    }
+
+    //lower bound of flowers not blooming
+    public int notBlooming(int[] start, int index) {
+        int left = 0; 
+        int right = start.length;
+
+        while (left<right) {
+            int mid = left + (right-left)/2;
+            if (start[mid] < index) {
+                left = mid + 1;
+            } else {
+                right = mid;
+            }
+        }
+        return right;
+    }
+}