野人传教士问题java

野人传教士问题是一个经典的计算机科学问题，它涉及到如何将三个传教士和三个野人从一岸的河边运送到另一岸，同时保证在任何时候传教士的数量都不少于野人的数量，否则野人会吃掉传教士。这个问题可以用深度优先搜索算法来解决。以下是用Java语言实现的代码示例：

import java.util.ArrayList;

public class MissionariesAndCannibals {

    public static void main(String[] args) {
        State start = new State(3, 3, true);
        State goal = new State(0, 0, false);
        ArrayList<State> path = new ArrayList<State>();
        if (search(start, goal, path)) {
            for (int i = path.size() - 1; i >= 0; i--) {
                System.out.println(path.get(i));
            }
        } else {
            System.out.println("No solution found.");
        }
    }

    public static boolean search(State node, State goal, ArrayList<State> path) {
        path.add(node);
        if (node.equals(goal)) {
            return true;
        }
        for (State child : node.getChildren()) {
            if (!path.contains(child) && search(child, goal, path)) {
                return true;
            }
        }
        path.remove(node);
        return false;
    }

    public static class State {
        int missionaries;
        int cannibals;
        boolean boat;

        public State(int missionaries, int cannibals, boolean boat) {
            this.missionaries = missionaries;
            this.cannibals = cannibals;
            this.boat = boat;
        }

        public ArrayList<State> getChildren() {
            ArrayList<State> children = new ArrayList<State>();
            int delta = boat ? -1 : 1;
            for (int m = 0; m <= 2; m++) {
                for (int c = 0; c <= 2; c++) {
                    if (m + c >= 1 && m + c <= 2) {
                        int newMissionaries = missionaries + delta * m;
                        int newCannibals = cannibals + delta * c;
                        if (newMissionaries >= 0 && newMissionaries <= 3 && newCannibals >= 0 && newCannibals <= 3
                                && (newMissionaries == 0 || newMissionaries >= newCannibals)
                                && (newMissionaries == 3 || newMissionaries <= newCannibals)) {
                            children.add(new State(newMissionaries, newCannibals, !boat));
                        }
                    }
                }
            }
            return children;
        }

        @Override
        public boolean equals(Object obj) {
            if (obj instanceof State) {
                State other = (State) obj;
                return missionaries == other.missionaries && cannibals == other.cannibals && boat == other.boat;
            } else {
                return false;
            }
        }

        @Override
        public String toString() {
            return "(" + missionaries + "," + cannibals + "," + (boat ? "left" : "right") + ")";
        }
    }
}

在上面的代码中，`State`类表示状态，包括传教士和野人的数量以及船的位置。`getChildren`方法返回当前状态的所有可能子状态。`search`方法使用深度优先搜索算法来搜索从初始状态到目标状态的路径。最后，`main`方法设置初始状态和目标状态，并调用`search`方法来搜索路径。