Problem 1482

Author: YuqiZ2020

0-Binary-Search/1482-Minimum-Number-of-Days-to-Make-m-Bouquets.java

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+/**
+ * Problem 1482: Minimum Number of Days to Make m Bouquets
+ * Prompt: Given an integer array bloomDay, an integer m and an integer k.
+ * We need to make m bouquets. To make a bouquet, you need to use k 
+ * adjacent flowers from the garden.
+ * The garden consists of n flowers, the ith flower will bloom in the 
+ * bloomDay[i] and then can be used in exactly one bouquet.
+ * Return the minimum number of days you need to wait to be able to make m 
+ * bouquets from the garden. If it is impossible to make m bouquets 
+ * return -1.
+ * Date: 07/07/2020
+ */
+class Solution {
+    public int minDays(int[] bloomDay, int m, int k) {
+        int left = 1; int right = 1000000000;
+        int len = bloomDay.length; 
+        if (len < m * k) return -1;
+        while (left < right)
+        {
+            int mid = left + (right - left) / 2;
+            int count = 0;
+            int bouq = 0;
+            for (int i = 0; i < len; ++i)
+            {
+                if (bloomDay[i] <= mid)
+                    count++;
+                else
+                {
+                    bouq += (count / k);
+                    count = 0;
+                }
+            }
+            bouq += (count / k);
+            if (bouq < m)
+                left = mid + 1;
+            else
+                right = mid;
+        }
+        return left;
+    }
+}
+
+/**
+ * Notes: Use binary search to find the best date. For each given date
+ * we can calculate out how many bouque we can make by finding concecutive
+ * flowers that bloomed and produce the caluclation. Then if we don't have
+ * enough flowers we can go to the right interval or got to the left interval
+ * for the other way around. 
+ */