Added KMP algorithm

Algorithms/dynamic-problem/CherryPickupII.java

@@ -0,0 +1,41 @@
+/**
+ * Created on: Jun 21, 2020
+ * Questions: https://leetcode.com/problems/cherry-pickup/
+ */
+public class CherryPickupII {
+
+    public static void main(String[] args) {
+        System.out.println(cherryPickup(new int[][]{{3,1,1}, {2,5,1}, {1,5,5},{2,1,1}}) + "= 24");
+
+        System.out.println(cherryPickup(new int[][]{{1, 1, -1}, {1, -1, 1}, {-1, 1, 1}}) + "= 4");
+        System.out.println(cherryPickup(new int[][]{{1}}) + "= 1");
+        System.out.println(cherryPickup(new int[][]{{1, 1, 1, 1, 0, 0, 0}, {0, 0, 0, 1, 0, 0, 0}, {0, 0, 0, 1, 0, 0, 1}, {1, 0, 0, 1, 0, 0, 0}, {0, 0, 0, 1, 0, 0, 0}, {0, 0, 0, 1, 0, 0, 0}, {0, 0, 0, 1, 1, 1, 1}}) +
+                "= 7");
+    }
+
+    public static int cherryPickup(int[][] grid) {
+        int rows = grid.length;
+        int cols = rows > 0 ? grid[0].length : 0;
+        Integer[][][] dp = new Integer[rows][cols][cols];
+        return helper(grid, 0, 0, cols - 1, dp, rows, cols);
+    }
+
+    private static int helper(int[][] grid, int row, int c1, int c2, Integer[][][] dp, int rows, int cols) {
+        if (row == rows) return 0;
+        if (c1 < 0 || c1 >= cols || c2 < 0 || c2 >= cols) return Integer.MIN_VALUE;
+        if (dp[row][c1][c2] != null) {
+            return dp[row][c1][c2];
+        }
+        int[] dirs = {-1, 0, 1};
+        int max = 0;
+        for (int d1 : dirs) {
+            for (int d2 : dirs) {
+                int next = helper(grid, row + 1, c1 + d1, c2 + d2, dp, rows, cols);
+                max = Math.max(max, next);
+            }
+        }
+        max += c1 == c2 ? grid[row][c1] : grid[row][c1] + grid[row][c2];
+        dp[row][c1][c2] = max;
+        return max;
+    }
+}

Algorithms/kmp/FindPatternInString.java

@@ -0,0 +1,62 @@
+import java.util.*;
+import java.io.*;
+
+/**
+ * Created on:  Feb 11, 2024
+ * Ref:
+ */
+
+public class FindPatternInString {
+
+    public static void main(String[] args) {
+        System.out.println(getPatternCount("abcaeabc", "abc"));
+    }
+
+    private static int getPatternCount(String str, String pattern) {
+        int count = 0, len = str.length(), p = pattern.length();
+//         Build lps.
+        int[] lps = new int[p];
+        buildLPS(pattern, lps);
+        int i = 0, j = 0;
+        while (i < len) {
+            if (str.charAt(i) == pattern.charAt(j)) {
+                i++;
+                j++;
+                if (j == p) {
+                    j = lps[j - 1];
+                }
+            } else {
+                if (j > 0) {
+//                    Find the previous prefix and suffix.
+                    j = lps[j - 1];
+                } else {
+//                    If there is no any previous prefix then
+                    i++;
+                }
+            }
+        }
+        return count;
+    }
+
+    private static void buildLPS(String pattern, int[] lps) {
+        int len = lps.length, pre = 0;
+        lps[0] = 0;
+        int i = 1;
+        while (i < len) {
+            if (pattern.charAt(i) == pattern.charAt(pre)) {
+                pre++;
+                lps[i] = pre;
+                i++;
+            } else {
+                if (pre != 0) {
+                    pre = lps[pre - 1];
+                } else {
+                    lps[i] = pre;
+                    i++;
+                }
+            }
+        }
+    }
+
+
+}