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BAEL-875 code refactoring (#2030)

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Hill-Climbing refactor
This commit is contained in:
Parth Karia 2017-06-09 18:27:29 +05:30 committed by maibin
parent 920167f5b7
commit 4552b8088c
1 changed files with 53 additions and 34 deletions
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87
algorithms/src/main/java/com/baeldung/algorithms/hillclimbing/HillClimbing.java
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@ -5,7 +5,6 @@ import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.Stack;
import java.util.stream.Collectors;
public class HillClimbing {
public static void main(String[] args) {
@ -79,24 +78,31 @@ public class HillClimbing {
return listOfStacks.stream()
.map(stack -> {
State tempState;
List<Stack<String>> tempStackList = new ArrayList<>(listOfStacks);
String block = stack.pop();
if (stack.size() == 0)
tempStackList.remove(stack);
tempState = pushElementToNewStack(tempStackList, block, currentStateHeuristics, goalStateStack);
if (tempState == null) {
tempState = pushElementToExistingStacks(stack, tempStackList, block, currentStateHeuristics, goalStateStack);
}
if (tempState == null)
stack.push(block);
return tempState;
return applyOperationsOnState(listOfStacks, stack, currentStateHeuristics, goalStateStack);
})
.filter(Objects::nonNull)
.findFirst()
.orElse(null);
}
/**
* This method applies operations on the current state to get a new state
*/
public State applyOperationsOnState(List<Stack<String>> listOfStacks, Stack<String> stack, int currentStateHeuristics, Stack<String> goalStateStack) {
State tempState;
List<Stack<String>> tempStackList = new ArrayList<>(listOfStacks);
String block = stack.pop();
if (stack.size() == 0)
tempStackList.remove(stack);
tempState = pushElementToNewStack(tempStackList, block, currentStateHeuristics, goalStateStack);
if (tempState == null) {
tempState = pushElementToExistingStacks(stack, tempStackList, block, currentStateHeuristics, goalStateStack);
}
if (tempState == null)
stack.push(block);
return tempState;
}
/**
* Operation to be applied on a state in order to find new states. This
* operation pushes an element into a new stack
@ -126,45 +132,58 @@ public class HillClimbing {
Optional<State> newState = currentStackList.stream()
.filter(stack -> stack != currentStack)
.map(stack -> {
stack.push(block);
int newStateHeuristics = getHeuristicsValue(currentStackList, goalStateStack);
if (newStateHeuristics > currentStateHeuristics) {
return new State(currentStackList, newStateHeuristics);
}
stack.pop();
return null;
return pushElementToStack(stack, block, currentStackList, currentStateHeuristics, goalStateStack);
})
.filter(Objects::nonNull)
.findFirst();
return newState.orElse(null);
}
/**
* This method pushes a block to the stack and returns new state if its closer to goal
*/
private State pushElementToStack(Stack stack, String block, List<Stack<String>> currentStackList, int currentStateHeuristics, Stack<String> goalStateStack) {
stack.push(block);
int newStateHeuristics = getHeuristicsValue(currentStackList, goalStateStack);
if (newStateHeuristics > currentStateHeuristics) {
return new State(currentStackList, newStateHeuristics);
}
stack.pop();
return null;
}
/**
* This method returns heuristics value for given state with respect to goal
* state
*/
public int getHeuristicsValue(List<Stack<String>> currentState, Stack<String> goalStateStack) {
Integer heuristicValue;
heuristicValue = currentState.stream()
.mapToInt(stack -> {
int stackHeuristics = 0;
boolean isPositioneCorrect = true;
int goalStartIndex = 0;
for (String currentBlock : stack) {
if (isPositioneCorrect && currentBlock.equals(goalStateStack.get(goalStartIndex))) {
stackHeuristics += goalStartIndex;
} else {
stackHeuristics -= goalStartIndex;
isPositioneCorrect = false;
}
goalStartIndex++;
}
return stackHeuristics;
return getHeuristicsValueForStack(stack, currentState, goalStateStack);
})
.sum();
return heuristicValue;
}
/**
* This method returns heuristics value for a particular stack
*/
public int getHeuristicsValueForStack(Stack<String> stack, List<Stack<String>> currentState, Stack<String> goalStateStack) {
int stackHeuristics = 0;
boolean isPositioneCorrect = true;
int goalStartIndex = 0;
for (String currentBlock : stack) {
if (isPositioneCorrect && currentBlock.equals(goalStateStack.get(goalStartIndex))) {
stackHeuristics += goalStartIndex;
} else {
stackHeuristics -= goalStartIndex;
isPositioneCorrect = false;
}
goalStartIndex++;
}
return stackHeuristics;
}
}