One Size Smaller

ViewController.mm

//
//  ViewController.mm
//  OneSizeSmaller
//
//  Created by MizushimaYusuke on 9/15/15.
//  Copyright (c) 2015 MizushimaYusuke. All rights reserved.
//

#import "ViewController.h"
#include <vector>
#include <memory>
using namespace std;

class FindOneSizeSmaller {
public:
    int find(vector<int> heightList, int key) {
        
        sort(heightList.begin(), heightList.end());
        
        int l = 0;
        int r = (int)heightList.size();
        while (l < r) {
            int mid = (l + r) / 2;
            if (heightList[mid] == key)
                return heightList[mid - 1];
            else if (key < heightList[mid])
                r = mid;
            else
                l = mid + 1;
        }
        return -1;
    }
};

@interface ViewController () {
    vector<int> heightList;
    NSMutableArray *bars;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor colorWithHue:0.7 saturation:1 brightness:0.4 alpha:1];
    

    for (int i=20; i<100; i++) {
        int h = 3 * i + arc4random() % 2;
        heightList.emplace_back(h);
    }
    random_shuffle(heightList.begin(), heightList.end());
    
    bars = [NSMutableArray array];
    for (int i=0; i<heightList.size(); i++) {
        UIView *bar = [[UIView alloc] initWithFrame:CGRectMake(50 + i * 7, 100, 7, heightList[i] / 2.0)];
        bar.layer.borderWidth = 1.5;
        bar.layer.borderColor = self.view.backgroundColor.CGColor;
        bar.tag = heightList[i];
        bar.backgroundColor = [UIColor whiteColor];
        [self.view addSubview:bar];
        
        [bars addObject:bar];
    }
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    
    CGPoint p = [[touches anyObject] locationInView:self.view];
    UIView *hit = [self.view hitTest:p withEvent:nil];
    if (hit.tag > 0) {
        [bars enumerateObjectsUsingBlock:^(UIView *v, NSUInteger idx, BOOL *stop) {
            v.backgroundColor = [UIColor whiteColor];
            [UIView animateWithDuration:0.1 animations:^{
                v.transform = CGAffineTransformIdentity;
            }];
        }];
        hit.backgroundColor = [UIColor yellowColor];
        
        shared_ptr<FindOneSizeSmaller> cppClass(new FindOneSizeSmaller());
        int oneSmallerHeight = cppClass->find(heightList, (int)hit.tag);
        
        UIView *oneSmaller = [self.view viewWithTag:oneSmallerHeight];
        if (oneSmaller) {
            oneSmaller.backgroundColor = [UIColor greenColor];
            [UIView animateWithDuration:1.0 animations:^{
                oneSmaller.transform = CGAffineTransformMakeTranslation(0, -30);
            }];
        }
    }
    
}
@end

http://lepetit-prince.net/ios/?p=4355