[FEATURE] Add Jump Search Algorithm Implementation in R (#216)

Author: iampratik13

searches/jump_search.r

@@ -0,0 +1,287 @@
+# Jump Search Algorithm Implementation in R
+# An efficient search algorithm for sorted arrays
+# Works by jumping ahead by fixed steps then performing linear search
+# Time complexity: O(√n) where n is the array length
+# Space complexity: O(1)
+
+library(R6)
+
+#' JumpSearch Class
+#' @description R6 class implementing the Jump Search algorithm
+#' @details Jump Search is a searching algorithm for sorted arrays that works by:
+#' 1. Dividing the array into blocks of size √n
+#' 2. Jumping ahead by √n steps until finding a block where target might be
+#' 3. Performing linear search within that block
+#' Advantages:
+#' - Better than linear search: O(√n) vs O(n)
+#' - Better for systems with slow backward iteration compared to binary search
+#' - Simple implementation
+#' Limitations:
+#' - Requires sorted array
+#' - Slower than binary search: O(√n) vs O(log n)
+JumpSearch <- R6Class(
+  "JumpSearch",
+  
+  public = list(
+    #' @description Initialize Jump Search
+    #' @param data Sorted array to search in
+    #' @param validate_sorted Whether to validate if array is sorted
+    initialize = function(data = NULL, validate_sorted = TRUE) {
+      if (!is.null(data)) {
+        private$validate_input(data, validate_sorted)
+        self$data <- data
+        private$n <- length(data)
+        private$optimal_jump <- floor(sqrt(private$n))
+      }
+      invisible(self)
+    },
+    
+    #' @description Search for a target value in the array
+    #' @param target Value to search for
+    #' @param jump_size Optional custom jump size (default: √n)
+    #' @return List containing index, number of comparisons, and success status
+    search = function(target, jump_size = NULL) {
+      if (is.null(self$data)) {
+        stop("No data available. Please initialize with data first.")
+      }
+      
+      # Use custom jump size or optimal jump size
+      step <- if (is.null(jump_size)) private$optimal_jump else jump_size
+      
+      if (step <= 0 || step != round(step)) {
+        stop("Jump size must be a positive integer")
+      }
+      
+      prev <- 0
+      comparisons <- 0
+      
+      # Jump through array to find the block where target might be
+      while (step <= private$n && self$data[step] < target) {
+        comparisons <- comparisons + 1
+        prev <- step
+        step <- step + private$optimal_jump
+      }
+      
+      # If we've jumped past the end, adjust step to not exceed n
+      if (prev >= private$n) {
+        return(list(
+          index = -1,
+          comparisons = comparisons,
+          found = FALSE
+        ))
+      }
+      
+      # Linear search in the identified block
+      while ((prev + 1) <= private$n && self$data[prev + 1] <= target) {
+        comparisons <- comparisons + 1
+        prev <- prev + 1
+        
+        if (self$data[prev] == target) {
+          return(list(
+            index = prev,
+            comparisons = comparisons,
+            found = TRUE
+          ))
+        }
+      }
+      
+      # Target not found
+      return(list(
+        index = -1,
+        comparisons = comparisons,
+        found = FALSE
+      ))
+    },
+    
+    #' @description Search for multiple targets
+    #' @param targets Vector of values to search for
+    #' @return List of search results for each target
+    search_multiple = function(targets) {
+      if (!is.numeric(targets)) {
+        stop("Targets must be numeric")
+      }
+      
+      results <- list()
+      for (i in seq_along(targets)) {
+        results[[i]] <- self$search(targets[i])
+        results[[i]]$target <- targets[i]
+      }
+      return(results)
+    },
+    
+    #' @description Find the optimal jump size for the current data
+    #' @return Optimal jump size (√n)
+    get_optimal_jump_size = function() {
+      if (is.null(self$data)) {
+        stop("No data available. Please initialize with data first.")
+      }
+      return(private$optimal_jump)
+    },
+    
+    #' @description Compare performance with different jump sizes
+    #' @param target Value to search for
+    #' @param jump_sizes Vector of jump sizes to test
+    #' @return Data frame with performance comparison
+    compare_jump_sizes = function(target, jump_sizes = NULL) {
+      if (is.null(self$data)) {
+        stop("No data available. Please initialize with data first.")
+      }
+      
+      if (is.null(jump_sizes)) {
+        jump_sizes <- c(
+          floor(sqrt(private$n) / 2),
+          private$optimal_jump,
+          floor(sqrt(private$n) * 2)
+        )
+      }
+      
+      results <- data.frame(
+        jump_size = numeric(),
+        comparisons = numeric(),
+        found = logical(),
+        stringsAsFactors = FALSE
+      )
+      
+      for (size in jump_sizes) {
+        if (size > 0 && size <= private$n) {
+          result <- self$search(target, jump_size = size)
+          results <- rbind(results, data.frame(
+            jump_size = size,
+            comparisons = result$comparisons,
+            found = result$found
+          ))
+        }
+      }
+      
+      return(results)
+    },
+    
+    #' @description Update the data array
+    #' @param new_data New sorted array
+    #' @param validate_sorted Whether to validate if array is sorted
+    update_data = function(new_data, validate_sorted = TRUE) {
+      private$validate_input(new_data, validate_sorted)
+      self$data <- new_data
+      private$n <- length(new_data)
+      private$optimal_jump <- floor(sqrt(private$n))
+      invisible(self)
+    },
+    
+    # Public fields
+    data = NULL
+  ),
+  
+  private = list(
+    n = NULL,
+    optimal_jump = NULL,
+    
+    validate_input = function(data, check_sorted) {
+      if (!is.numeric(data)) {
+        stop("Input data must be numeric")
+      }
+      if (any(is.na(data))) {
+        stop("Input data contains missing values")
+      }
+      if (length(data) == 0) {
+        stop("Input data cannot be empty")
+      }
+      if (check_sorted && !private$is_sorted(data)) {
+        stop("Input data must be sorted in ascending order")
+      }
+    },
+    
+    is_sorted = function(data) {
+      all(diff(data) >= 0)
+    }
+  )
+)
+
+# Demonstration
+demonstrate_jump_search <- function() {
+  cat("=== Jump Search Algorithm Demo ===\n\n")
+  
+  # Example 1: Basic usage
+  cat("Example 1: Basic jump search\n")
+  data <- c(1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29)
+  cat("Sorted array:", paste(data, collapse = ", "), "\n")
+  
+  js <- JumpSearch$new(data)
+  cat(sprintf("Array size: %d, Optimal jump size: %d\n\n", 
+              length(data), js$get_optimal_jump_size()))
+  
+  targets <- c(7, 19, 30)
+  for (target in targets) {
+    result <- js$search(target)
+    if (result$found) {
+      cat(sprintf("Target %d found at index %d (comparisons: %d)\n", 
+                  target, result$index, result$comparisons))
+    } else {
+      cat(sprintf("Target %d not found (comparisons: %d)\n", 
+                  target, result$comparisons))
+    }
+  }
+  
+  # Example 2: Larger dataset
+  cat("\nExample 2: Larger dataset\n")
+  set.seed(42)
+  large_data <- sort(sample(1:1000, 100))
+  js2 <- JumpSearch$new(large_data)
+  
+  cat(sprintf("Array size: %d, Optimal jump size: %d\n", 
+              length(large_data), js2$get_optimal_jump_size()))
+  
+  search_targets <- c(large_data[25], large_data[75], 999)
+  results <- js2$search_multiple(search_targets)
+  
+  cat("\nMultiple search results:\n")
+  for (i in seq_along(results)) {
+    res <- results[[i]]
+    cat(sprintf("Target %d: %s (index: %d, comparisons: %d)\n",
+                res$target,
+                ifelse(res$found, "Found", "Not found"),
+                res$index,
+                res$comparisons))
+  }
+  
+  # Example 3: Jump size comparison
+  cat("\nExample 3: Comparing different jump sizes\n")
+  test_data <- 1:100
+  js3 <- JumpSearch$new(test_data)
+  target <- 87
+  
+  comparison <- js3$compare_jump_sizes(target)
+  cat(sprintf("Searching for %d in array of size %d:\n\n", target, length(test_data)))
+  print(comparison)
+  
+  # Example 4: Performance analysis
+  cat("\nExample 4: Performance analysis\n")
+  sizes <- c(100, 1000, 10000)
+  
+  cat("Average comparisons for different array sizes:\n")
+  for (n in sizes) {
+    test_array <- 1:n
+    js_test <- JumpSearch$new(test_array)
+    
+    # Test multiple searches
+    num_tests <- 20
+    total_comps <- 0
+    for (i in 1:num_tests) {
+      target <- sample(test_array, 1)
+      result <- js_test$search(target)
+      total_comps <- total_comps + result$comparisons
+    }
+    
+    avg_comps <- total_comps / num_tests
+    theoretical_bound <- sqrt(n)
+    
+    cat(sprintf("n = %5d: Avg comparisons = %.1f, Theoretical O(√n) = %.1f\n",
+                n, avg_comps, theoretical_bound))
+  }
+  
+  cat("\n=== Demo Complete ===\n")
+}
+
+# Run demonstration if not in interactive mode
+if (!interactive()) {
+  demonstrate_jump_search()
+}