从 NSArray 中找到小于给定数字的最大数字 [英] Find the largest number from NSArray that is smaller than the given number

问题描述

假设我有一个已排序的整数数组 int[]，并且我想搜索与某个输入数字最接近的较小值.

Suppose I have a sorted array of integers int[], and I want to search the closest smaller value to some input number.

例如如果数组包含1、23、57、59、120，输入为109，输出应为59.我已经尝试过这个，但它没有按需要工作.

for example if the array contains 1, 23, 57, 59, 120 and the input is 109, the output should be 59. I have tried this but it is not working out as needed.

NSTimeInterval currentTime = self.player.currentTime;
NSInteger playerTime=currentTime;
NSUInteger index = [_timesArray indexOfObject:@(playerTime)
                                inSortedRange:NSMakeRange(0, _timesArray.count-1)
                                      options:NSBinarySearchingFirstEqual | NSBinarySearchingInsertionIndex
                              usingComparator:^(id a, id b) {
                                  return [a compare:b];
                              }];

推荐答案

您的代码与您提供的示例数据一起按预期工作:

Your code does work as expected with the example data you gave:

NSArray *_timesArray = @[@1, @23, @57, @59, @120];
NSTimeInterval currentTime = 109;
NSInteger playerTime=currentTime;
NSUInteger index = [_timesArray indexOfObject:@(playerTime)
                                inSortedRange:NSMakeRange(0, _timesArray.count-1)
                                      options:NSBinarySearchingFirstEqual | NSBinarySearchingInsertionIndex
                              usingComparator:^(id a, id b) {
                                  return [a compare:b];
                              }];
NSLog(@"Index: %lu", (unsigned long)index);

输出:

Index: 4

检查您的输入.很可能它们不是您认为的那样.

Check your inputs. Likely they are not what you think they are.

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