Question

我有一个关于java中嵌套for循环的初学者问题。

vartical-align:top

所以这是我的跟踪表

int sum = 0;
for(int i = 1; i < 3; i++){
    for(int j = i; j>= 0; j--){
        sum += j;
    }
}

我的问题是为什么循环结束时的输出是4？是因为3 + 1？

Answer 1

您的跟踪表是错误的。这是正确的：

您对j（第二列）的所有值求和，基本上为1 + 0 + 2 + 1 + 0 = 4。

Answer 2

实际上我们需要对您的表格结果进行更正：

i j sum
1 1 1
  0 1
2 2 2 (sum is 2+1(existing sum, sum is not 0 anymore) )
  1 3 (sum is 3 + 1 = 4)
  0 3 (sum is 4+ 0 = 4)

Answer 3

输出为4，因为Trialtime type Track time Notes Athlete Trialtime type Track time Notes Athlete 20170101 07:15:00 07:15:00 Warmup ABC 85.2 Initial warmup Jon 20170101 07:45:00 07:45:00 Sprint1 ABC 59.44 First Sprint Jon 20170101 08:30:00 08:30:00 TRIAL ABC 57.21 Final attempt Jon 20170101 08:00:00 08:00:00 Warmup ABC 120.51 Initial warmup Bill 20170101 08:40:05 08:40:05 Sprint1 ABC 61.35 First Sprint Bill 20170101 09:15:00 09:15:00 Sprint2 ABC 60.08 Second Sprint Bill 20170101 10:30:00 10:30:00 TRIAL ABC 60.37 Final attempt Bill 20170101 07:15:00 07:15:00 Warmup ABC 85.2 Initial warmup Jon 20170101 07:45:00 07:45:00 Sprint1 ABC 59.44 First Sprint Jon 20170101 08:30:00 08:30:00 TRIAL ABC 57.21 Final attempt Jon 20170101 08:00:00 08:00:00 Warmup ABC 120.51 Initial warmup Bill 20170101 08:40:05 08:40:05 Sprint1 ABC 61.35 First Sprint Bill 20170101 09:15:00 09:15:00 Sprint2 ABC 60.08 Second Sprint Bill 20170101 10:30:00 10:30:00 TRIAL ABC 60.37 Final attempt Bill Trialtime type Track time Notes Athlete 201701023 07:15:00 07:15:00 Warmup ABC 85.2 Initial warmup Jon 201701023 07:45:00 07:45:00 Sprint1 ABC 59.44 First Sprint Jon 201701023 08:30:00 08:30:00 TRIAL ABC 57.21 Final attempt Jon 201701023 08:00:00 08:00:00 Warmup ABC 120.51 Initial warmup Bill 201701023 08:40:05 08:40:05 Sprint1 ABC 61.35 First Sprint Bill 201701023 09:15:00 09:15:00 Sprint2 ABC 60.08 Second Sprint Bill 201701023 10:30:00 10:30:00 TRIAL ABC 60.37 Final attempt Bill 201701023 07:15:00 07:15:00 Warmup ABC 85.2 Initial warmup Jon 201701023 07:45:00 07:45:00 Sprint1 ABC 59.44 First Sprint Jon 201701023 08:30:00 08:30:00 TRIAL ABC 57.21 Final attempt Jon 201701023 08:00:00 08:00:00 Warmup ABC 120.51 Initial warmup Bill 201701023 08:40:05 08:40:05 Sprint1 ABC 61.35 First Sprint Bill 201701023 09:15:00 09:15:00 Sprint2 ABC 60.08 Second Sprint Bill 201701023 10:30:00 10:30:00 TRIAL ABC 60.37 Final attempt Bill为：

sum

首先添加0 + 1 + 2 + 1 = = 4，然后1和2。您的循环将所有三角形数字加在3以下。三角形数字是从1到1的数字之和。这些是n，1，3，6等。

嵌套for循环Java混淆

3 个答案: