add PalindromicSubstrings and PaintHouse

company/facebook/PalindromicSubstrings.java

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+//Given a string, your task is to count how many palindromic substrings in this string.
+//The substrings with different start indexes or end indexes are counted as different substrings 
+//even they consist of same characters.
+
+//Example 1:
+//Input: "abc"
+//Output: 3
+//Explanation: Three palindromic strings: "a", "b", "c".
+//Example 2:
+//Input: "aaa"
+//Output: 6
+//Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa".
+//Note:
+//The input string length won't exceed 1000.
+
+class PalindromicSubstrings {
+    int result = 0;
+    public int countSubstrings(String s) {
+        if(s == null || s.length() == 0) {
+            return 0;
+        }
+
+        for(int i = 0; i < s.length(); i++) {
+            extendPalindrome(s, i, i);
+            extendPalindrome(s, i, i + 1);
+        }
+
+        return result;
+    }
+
+    public void extendPalindrome(String s, int left, int right) {
+        while(left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {
+            result++;
+            left--;
+            right++;
+        }
+    }
+}
+

company/linkedin/PaintHouse.java

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+//There are a row of n houses, each house can be painted with one of the three colors: red, blue or green. 
+//The cost of painting each house with a certain color is different. You have to paint all the houses such 
+//that no two adjacent houses have the same color.
+
+//The cost of painting each house with a certain color is represented by a n x 3 cost matrix. For example, 
+//costs[0][0] is the cost of painting house 0 with color red; costs[1][2] is the cost of painting house 1 
+//with color green, and so on... Find the minimum cost to paint all houses.
+
+//Note:
+//All costs are positive integers.
+
+class PaintHouse {
+    public int minCost(int[][] costs) {
+        if(costs == null || costs.length == 0) {
+            return 0;
+        }
+
+        for(int i = 1; i < costs.length; i++) {
+            costs[i][0] += Math.min(costs[i - 1][1], costs[i - 1][2]);
+            costs[i][1] += Math.min(costs[i - 1][0], costs[i - 1][2]);
+            costs[i][2] += Math.min(costs[i - 1][0], costs[i - 1][1]);
+        }
+
+        return Math.min(Math.min(costs[costs.length - 1][0], costs[costs.length - 1][1]), costs[costs.length - 1][2]);
+    }
+}

company/linkedin/PalindromicSubstrings.java

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+//Given a string, your task is to count how many palindromic substrings in this string.
+//The substrings with different start indexes or end indexes are counted as different substrings 
+//even they consist of same characters.
+
+//Example 1:
+//Input: "abc"
+//Output: 3
+//Explanation: Three palindromic strings: "a", "b", "c".
+//Example 2:
+//Input: "aaa"
+//Output: 6
+//Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa".
+//Note:
+//The input string length won't exceed 1000.
+
+class PalindromicSubstrings {
+    int result = 0;
+    public int countSubstrings(String s) {
+        if(s == null || s.length() == 0) {
+            return 0;
+        }
+
+        for(int i = 0; i < s.length(); i++) {
+            extendPalindrome(s, i, i);
+            extendPalindrome(s, i, i + 1);
+        }
+
+        return result;
+    }
+
+    public void extendPalindrome(String s, int left, int right) {
+        while(left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {
+            result++;
+            left--;
+            right++;
+        }
+    }
+}
+

leetcode/dynamic-programming/PaintHouse.java

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+//There are a row of n houses, each house can be painted with one of the three colors: red, blue or green. 
+//The cost of painting each house with a certain color is different. You have to paint all the houses such 
+//that no two adjacent houses have the same color.
+
+//The cost of painting each house with a certain color is represented by a n x 3 cost matrix. For example, 
+//costs[0][0] is the cost of painting house 0 with color red; costs[1][2] is the cost of painting house 1 
+//with color green, and so on... Find the minimum cost to paint all houses.
+
+//Note:
+//All costs are positive integers.
+
+class PaintHouse {
+    public int minCost(int[][] costs) {
+        if(costs == null || costs.length == 0) {
+            return 0;
+        }
+
+        for(int i = 1; i < costs.length; i++) {
+            costs[i][0] += Math.min(costs[i - 1][1], costs[i - 1][2]);
+            costs[i][1] += Math.min(costs[i - 1][0], costs[i - 1][2]);
+            costs[i][2] += Math.min(costs[i - 1][0], costs[i - 1][1]);
+        }
+
+        return Math.min(Math.min(costs[costs.length - 1][0], costs[costs.length - 1][1]), costs[costs.length - 1][2]);
+    }
+}
+

leetcode/dynamic-programming/PalindromicSubstrings.java

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+//Given a string, your task is to count how many palindromic substrings in this string.
+//The substrings with different start indexes or end indexes are counted as different substrings 
+//even they consist of same characters.
+
+//Example 1:
+//Input: "abc"
+//Output: 3
+//Explanation: Three palindromic strings: "a", "b", "c".
+//Example 2:
+//Input: "aaa"
+//Output: 6
+//Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa".
+//Note:
+//The input string length won't exceed 1000.
+
+class PalindromicSubstrings {
+    int result = 0;
+    public int countSubstrings(String s) {
+        if(s == null || s.length() == 0) {
+            return 0;
+        }
+
+        for(int i = 0; i < s.length(); i++) {
+            extendPalindrome(s, i, i);
+            extendPalindrome(s, i, i + 1);
+        }
+
+        return result;
+    }
+
+    public void extendPalindrome(String s, int left, int right) {
+        while(left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {
+            result++;
+            left--;
+            right++;
+        }
+    }
+}
+

leetcode/string/PalindromicSubstrings.java

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+//Given a string, your task is to count how many palindromic substrings in this string.
+//The substrings with different start indexes or end indexes are counted as different substrings 
+//even they consist of same characters.
+
+//Example 1:
+//Input: "abc"
+//Output: 3
+//Explanation: Three palindromic strings: "a", "b", "c".
+//Example 2:
+//Input: "aaa"
+//Output: 6
+//Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa".
+//Note:
+//The input string length won't exceed 1000.
+
+class PalindromicSubstrings {
+    int result = 0;
+    public int countSubstrings(String s) {
+        if(s == null || s.length() == 0) {
+            return 0;
+        }
+
+        for(int i = 0; i < s.length(); i++) {
+            extendPalindrome(s, i, i);
+            extendPalindrome(s, i, i + 1);
+        }
+
+        return result;
+    }
+
+    public void extendPalindrome(String s, int left, int right) {
+        while(left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {
+            result++;
+            left--;
+            right++;
+        }
+    }
+}