iOS实现二叉树数据结构

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#头文件

@interface YFTree<__covariant ObjectType> : NSObject

/**
根节点的值
*/
@property (nonatomic, strong) ObjectType rootData;

@property (nonatomic, strong) YFTree *leftTree;

@property (nonatomic, strong) YFTree *rightTree;

+ (instancetype)treeWithRootData:(ObjectType)rootData;

+ (instancetype)treeWithRootDate:(ObjectType)rootData leftTree:(YFTree *)leftTree rightTree:(YFTree *)rightTree;

/**
返回前序遍历的数据组

@return 遍历的数据
*/
- (NSArray<ObjectType> *)preOrder;

/**
返回中序遍历的数据组

@return 遍历的数据
*/
- (NSArray<ObjectType> *)inOrder;

/**
返回后序遍历的数据组

@return 遍历的数据
*/
- (NSArray<ObjectType> *)postOrder;

/**
逐层遍历

@return 遍历的数据
*/
- (NSArray<ObjectType> *)levelOrder;

@end

#实现文件

@implementation YFTree

+ (instancetype)treeWithRootData:(id)rootData {
YFTree *newObj = [YFTree new];
newObj.rootData = rootData;
return newObj;
}

+ (instancetype)treeWithRootDate:(id)rootData leftTree:(YFTree *)leftTree rightTree:(YFTree *)rightTree {

YFTree *newObj = [YFTree new];
newObj.rootData = rootData;
newObj.leftTree = leftTree;
newObj.rightTree = rightTree;

return newObj;
}

- (NSArray *)preOrder {

NSMutableArray *objects = [[NSMutableArray alloc] init];

if (_rootData) {

[objects addObject:_rootData];
}

if (_leftTree) {

[objects addObjectsFromArray:[_leftTree preOrder]];
}


if (_rightTree) {

[objects addObjectsFromArray:[_rightTree preOrder]];
}


return [objects copy];
}

- (NSArray *)inOrder {

NSMutableArray *objects = [[NSMutableArray alloc] init];

if (_leftTree) {

[objects addObjectsFromArray:[_leftTree preOrder]];
}

if (_rootData) {

[objects addObject:_rootData];
}


if (_rightTree) {

[objects addObjectsFromArray:[_rightTree preOrder]];
}


return [objects copy];
}

- (NSArray *)postOrder {

NSMutableArray *objects = [[NSMutableArray alloc] init];


if (_leftTree) {

[objects addObjectsFromArray:[_leftTree preOrder]];
}


if (_rightTree) {

[objects addObjectsFromArray:[_rightTree preOrder]];
}

if (_rootData) {

[objects addObject:_rootData];
}


return [objects copy];

}

- (NSArray *)levelOrder {

//添加首个元素
NSMutableArray *objects = [[NSMutableArray alloc] init];
[objects addObject:_rootData];


NSMutableArray *bufferQueue = [[NSMutableArray alloc] init];
[bufferQueue addObject:_leftTree];
[bufferQueue addObject:_rightTree];

YFTree *markTree;

while ([bufferQueue count] > 0) {

markTree = [bufferQueue firstObject];


[objects addObject:markTree.rootData];

if (markTree.leftTree) {
[bufferQueue addObject:markTree.leftTree];
}

if (markTree.rightTree) {
[bufferQueue addObject:markTree.rightTree];
}

[bufferQueue removeObject:markTree];

}



return [objects copy];

}

@end

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