一个（数字）数组任意组合相加等于一个常数求出数组中的组合

1 将传进数据数组排序
2 递归求和 （当相加大于特定值 进行内部递归）
1 将数组排序

-(void)textSum:(NSArray *)numArray targetNum:(float)targetNum{
    NSMutableArray *array = [NSMutableArray arrayWithArray:numArray];
    //先排序/Users/amc/Desktop/choose/choose
    for (int i = 0; i < array.count; ++i) {
        // 从水底往水面浮，所以从最后一个开始
        for (NSInteger j = array.count-1; j > i; j--) {
            // 后者比前者还小，将需要交换
            if ([array[j] intValue] < [array[j - 1] intValue]) {
                [array exchangeObjectAtIndex:j withObjectAtIndex:j-1];
            }
        }
    }
    self.array = array;
    self.targetNum = targetNum;
    for (int i = 0; i < array.count; i++) {
        NSMutableArray *addArray = [NSMutableArray array];
        [self printNum:i addArray:addArray];
    }
}

2 判定数组之和 内递归的实现

-(BOOL)printNum:(NSInteger)index addArray:(NSMutableArray *)addArray{
    [addArray addObject:self.array[index]];
    float sum = [self sum:addArray];
//    NSLog(@"111%@",addArray);
    if (sum == self.targetNum) {
//        NSLog(@"%@",addArray);
        [addArray removeLastObject];
        return YES;
    }else if (sum >self.targetNum){
        [addArray removeLastObject];
        return NO;
    }else{
        for (NSInteger i = index+1; i < self.array.count; i++) {
            //递归内循环
            if (![self printNum:i addArray:addArray]) {
                break;
            }
        }
        [addArray removeLastObject];
        return YES;
    }
}

3 数组求和

-(CGFloat)sum:(NSArray *)array{
    CGFloat sum = 0;
    for (NSString *str in array) {
        sum += [str floatValue];
    }
    return sum;
}