[問題] For迴圈 和 array 執行速度問題
大家好 小弟我有些觀念不是很清楚想請教大家
1.
for(i=0;i<m;i++)
for(j=0;j<n;j++)
{
//do something
}
2.
for(i=0;i<m*n;i++)
{
//do something
}
有個同學跟我說2跑的會比1快,請問這是為什麼呢? 不是都是跑了m*n次?
另外還有個類似的問題
3.
for(i=0;i<m;i++)
for(j=0;j<n;j++)
{
array_2D[i][j]=some operation;
}
4.
for(i=0;i<m;i++)
for(j=0;j<n;j++)
{
array_1D[i*m+j]=some operation;
}
那個同學又跟我說4比3快,但是大小一樣,只有2D跟1D的差別,請問他說的是對的嗎?
我原以為速度上1=2, 3=4, 但是被他這麼一說我有點被搞混了
煩請各位解答 謝謝
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