九章算法人工智能集训营2022
Objective-C语言实现：
- (NSArray *)mergeWithArray:(NSArray *)sourceArray
startIndex:(NSInteger)startIndex
midIndex:(NSInteger)midIndex
endIndex:(NSInteger)endIndex{
NSMutableArray *sourceMutableArray = [NSMutableArray arrayWithArray:sourceArray];
NSMutableArray *tempMutableArray = [[NSMutableArray alloc] init];
NSInteger i = startIndex;
NSInteger j = midIndex + 1;
NSInteger k = startIndex;
while (i != midIndex && j != endIndex){
if (sourceMutableArray[i] > sourceMutableArray[j]) {
//tempMutableArray[k] = sourceMutableArray[j];
[tempMutableArray replaceObjectAtIndex:k withObject:sourceMutableArray[j]];
k ++;
j ++;
}else{
//tempMutableArray[k] = sourceMutableArray[i];
[tempMutableArray replaceObjectAtIndex:k withObject:sourceMutableArray[i]];
k ++;
i ++;
}
}
while (i != midIndex + 1) {
[tempMutableArray replaceObjectAtIndex:k withObject:sourceMutableArray[i]];
k ++;
i ++;
}
while (j != endIndex + 1) {
[tempMutableArray replaceObjectAtIndex:k withObject:sourceMutableArray[j]];
k ++;
j ++;
}
for (i = startIndex; i < endIndex; i ++) {
[sourceMutableArray replaceObjectAtIndex:i withObject:tempMutableArray[i]];
}
return sourceMutableArray;}- (NSArray *)mergeSortWithArray:(NSArray *)sourceArray
startIndex:(NSInteger)startIndex
endIndex:(NSInteger)endIndex{
if (startIndex < endIndex) {
NSInteger midIndex = (startIndex + endIndex)/2;
NSArray *tempArray = [self mergeSortWithArray:sourceArray
startIndex:startIndex
endIndex:endIndex];
NSArray *tempArray2 = [self mergeSortWithArray:tempArray
startIndex:midIndex + 1
endIndex:endIndex];
return [self mergeWithArray:tempArray2
startIndex:startIndex
midIndex:midIndex
endIndex:endIndex];
}
return nil;}
