键索引计数法适合于整数分为较小的简单排序方法，基本的步骤分为四步:
1.统计每个分类出现的次数；
2.将分类的次数转换为对应的索引；
3.通过中间数组按照分类的权重对原始数组排序；
4.将排序之后中间数组赋值给原始数组；
基础定义
首先定义排序需要的需要类:
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@
interface
keyIndexModel:NSObject
@property (assign,nonatomic) NSInteger key;
@property (strong,nonatomic) NSString *value;
-(instancetype)initWithKeyValue:(NSInteger)key value:(NSString *)value;
@end
@
interface
KeyIndexSort : NSObject
-(
void
)sort:(NSMutableArray *)dataSource categoryNumber:(NSInteger)number;
@end
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实现具体排序方法:
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-(
void
)sort:(NSMutableArray *)dataSource categoryNumber:(NSInteger)number{
NSInteger len=[dataSource count];
NSMutableArray *tempArr=[[NSMutableArray alloc]initWithCapacity:1];
//http://www.cnblogs.com/xiaofeixiang/
for
(NSInteger i=0; i<len; i++) {
[tempArr addObject:[NSNull
null
]];
}
NSMutableArray *count=[[NSMutableArray alloc]initWithCapacity:1];
for
(NSInteger i=0; i<number+1; i++) {
[count addObject:[NSNumber numberWithInteger:0]];
}
//统计每个分类的次数
for
(NSInteger i=0;i<len; i++) {
keyIndexModel *model=dataSource[i];
count[model.key+1]=[NSNumber numberWithInteger:[count[model.key+1] integerValue]+1];
}
//将出现的次数转换为索引，第一组3次，第二组5次，因此对应第三组开始的索引是8
for
(NSInteger j=0; j<number; j++) {
count[j+1]=[NSNumber numberWithInteger:[count[j] integerValue]+[count[j+1] integerValue]];
}
//将元素从上到下分类
for
(NSInteger m=0; m<len; m++) {
keyIndexModel *model=dataSource[m];
tempArr[[count[model.key] integerValue]]=model;
count[model.key]=[NSNumber numberWithInteger:[count[model.key] integerValue]+1];
}
//重新排序赋值
for
(NSInteger i=0; i<len; i++) {
dataSource[i]=tempArr[i];
}
}
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排序测试
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NSMutableArray *dataSource=[[NSMutableArray alloc]initWithCapacity:1];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:0 value:
@"FlyElephant"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:1 value:
@"keso"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:2 value:
@"中山郎"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:3 value:
@"http://www.cnblogs.com/xiaofeixiang/"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:3 value:
@"iOS技术交流:228407086"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:2 value:
@"北京"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:1 value:
@"上海"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:3 value:
@"深圳"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:2 value:
@"广州"
]];
[dataSource addObject: [[keyIndexModel alloc]initWithKeyValue:0 value:
@"河南"
]];
KeyIndexSort *indexSort=[[KeyIndexSort alloc]init];
[indexSort sort:dataSource categoryNumber:5];
[dataSource enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
keyIndexModel *model=obj;
NSLog(
@"%ld--%@"
,idx,model.value);
}];
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排序结果:
本文转自Fly_Elephant博客园博客，原文链接：http://www.cnblogs.com/xiaofeixiang/p/4855240.html，如需转载请自行联系原作者
