[LEET-458] add 458

Author: fishercoder1534

leetcode-algorithms/README.md

@@ -29,6 +29,7 @@
 |462|[Minimum Moves to Equal Array Elements II](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/MinimumMovestoEqualArrayElementsII.java) | O(nlogn) |O(1) | Medium|
 |461|[Hamming Distance](https://leetcode.com/problems/hamming-distance/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/HammingDistance.java) | O(n) |O(1) | Easy|
 |459|[Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/RepeatedSubstringPattern.java)| O(n)|O(n) | Easy| KMP
+|458|[Poor Pigs](https://leetcode.com/problems/poor-pigs/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/PoorPigs.java) | O(1) |O(1) | Easy| Math
 |456|[132 Pattern](https://leetcode.com/problems/132-pattern/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/_132Pattern.java) | O(n) |O(n) | Medium| Stack
 |455|[Assign Cookies](https://leetcode.com/problems/assign-cookies/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/AssignCookies.java)| O(n)|O(1) | Easy|
 |454|[4Sum II](https://leetcode.com/problems/4sum-ii/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/_4SumII.java) | O(n) |O(n) | Medium| HashMap

leetcode-algorithms/src/main/java/com/stevesun/solutions/PoorPigs.java

@@ -0,0 +1,27 @@
+package com.stevesun.solutions;
+
+/**
+ * There are 1000 buckets, one and only one of them contains poison, the rest are filled with water. They all look the same. If a pig drinks that poison it will die within 15 minutes. What is the minimum amount of pigs you need to figure out which bucket contains the poison within one hour.
+
+ Answer this question, and write an algorithm for the follow-up general case.
+
+ Follow-up:
+
+ If there are n buckets and a pig drinking poison will die within m minutes, how many pigs (x) you need to figure out the "poison" bucket within p minutes? There is exact one bucket with poison.
+ */
+public class PoorPigs {
+
+    public int poorPigs(int buckets, int minutesToDie, int minutesToTest) {
+        if (buckets--==1){
+            return 0;
+        }
+        int base=minutesToTest/minutesToDie+1;
+        int count=0;
+        while (buckets>0){
+            buckets/=base;
+            count++;
+        }
+        return count;
+    }
+
+}

leetcode-algorithms/src/test/java/com/stevesun/PoorPigsTest.java

@@ -0,0 +1,58 @@
+package com.stevesun;
+
+import com.stevesun.solutions.PoorPigs;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static junit.framework.Assert.assertEquals;
+
+public class PoorPigsTest {
+    private static PoorPigs test;
+    private static int expected;
+    private static int actual;
+    private static int buckets;
+    private static int minutesToDie;
+    private static int minutesToTest;
+
+    @BeforeClass
+    public static void setup(){
+        test = new PoorPigs();
+    }
+
+    @Before
+    public void setupForEachTest(){
+        expected = 0;
+        actual = 0;
+    }
+
+    @Test
+    public void test1(){
+        buckets = 1000;
+        minutesToDie = 15;
+        minutesToTest = 60;
+        expected = 5;
+        actual = test.poorPigs(buckets, minutesToDie, minutesToTest);
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void test2(){
+        buckets = 1;
+        minutesToDie = 1;
+        minutesToTest = 1;
+        expected = 0;
+        actual = test.poorPigs(buckets, minutesToDie, minutesToTest);
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void test3(){
+        buckets = 1000;
+        minutesToDie = 12;
+        minutesToTest = 60;
+        expected = 4;
+        actual = test.poorPigs(buckets, minutesToDie, minutesToTest);
+        assertEquals(expected, actual);
+    }
+}