Fast sorting (detailed explanation) and sorting (detailed explanation)

Fast sorting (detailed explanation) and sorting (detailed explanation)

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Description:

Data to be sorted is divided into two independent parts by one sort. All the data in one part is smaller than all the data in the other part, then, sort the two data parts by using this method. The entire sorting process can be recursive to convert the entire data into an ordered sequence.

The average time complexity of quick sorting is O (NlogN), which is a Sort version of Bubble sorting.

Method: The "binary" principle is used for quick sorting. The steps are as follows:

1) set two variables I and j. When the sorting starts: I = 0, j = n-1; 2) the first array value is used as the comparison value and saved to temp first, that is, temp = A [0]; 3) then j --, search forward, find the value less than temp, because s [I] is saved in temp, so assign A value directly, s [I] = s [j] 4) Then I ++ searches backward and finds the value greater than temp, because the value of s [j] is stored in s [I] in step 1, assign a value directly, s [j] = s [I], and then j --, avoid endless loops (5) Repeat steps 3rd and 4 until I = j. Finally, return the temp value to 6 in s [I]) and then use the "binary" idea, take I as the dividing line, split into two arrays s [0, I-1], s [I + 1, n-1] and start sorting again

Take array 6 4 7 1 2 as an example:

The Code is as follows:

# Include "stdio. h "void find_frst (int * s, int lift, int right) {int I = lift, j = right, temp; // (1) initialize I, j if (lift> = right) return; temp = s [I]; // (2) Compare the values with the first array, save to temp while (I <j) {while (j> I & s [j]> = temp) // (3) j --, find the small value j --; s [I] = s [j]; // Save the small value to while (I <j & s [I] <= temp) on s [I) // (4) I ++, find I ++; s [j --] = s [I]; // Save the cursor to s [j]} s [I] = temp; // (5) Place the Compare value on s [I]/* (6) split into two arrays s [0, I-1], s [I + 1, n-1] and start sorting */find_frst (s, lift, I-1); // left find_frst (s, I + 1, right); // right} int main () {int I = 0, s [100], n; scanf ("% d", & n ); for (I = 0; I <n; I ++) scanf ("% d", & s [I]); find_frst (s, 0, n-1 ); for (I = 0; I <n; I ++) printf ("% 3d", s [I]); // print printf ("\ n ");}