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POJ 2299:Ultra-QuickSort
Ultra-QuickSort
Time Limit: 7000MS | Memory Limit: 65536K | |
Total Submissions: 39397 | Accepted: 14204 |
Description
In this problem, you have to analyze a particular sorting algorithm. The algorithm processes a sequence of n distinct integers by swapping two adjacent sequence elements until the sequence is sorted in ascending order. For the input sequence
9 1 0 5 4 ,
Ultra-QuickSort produces the output
0 1 4 5 9 .
Your task is to determine how many swap operations Ultra-QuickSort needs to perform in order to sort a given input sequence.
Ultra-QuickSort produces the output
Your task is to determine how many swap operations Ultra-QuickSort needs to perform in order to sort a given input sequence.
Input
The input contains several test cases. Every test case begins with a line that contains a single integer n < 500,000 -- the length of the input sequence. Each of the the following n lines contains a single integer 0 ≤ a[i] ≤ 999,999,999, the i-th input sequence element. Input is terminated by a sequence of length n = 0. This sequence must not be processed.
Output
For every input sequence, your program prints a single line containing an integer number op, the minimum number of swap operations necessary to sort the given input sequence.
Sample Input
5 9 1 0 5 4 3 1 2 3 0
Sample Output
6 0
并归排序。
另外,此题有一坑就是结果会超int32;具体可以参考:点击打开链接
我写的代码如下:
#include<cstdio> #include<stdlib.h> #include<cstring> #include<algorithm> #include<iostream> using namespace std; const int M = 500000 + 5; int n, A[M], T[M], i; long long merge_sort(int l, int r, int *A) { if (r - l < 1) return 0; int mid = (l + r) / 2; long long ans = merge_sort(l, mid, A) + merge_sort(mid + 1, r, A); i = l; int p = l, q = mid + 1; while (p <= mid && q <= r) { if(A[p] <= A[q]) T[i++] = A[p++]; else { ans += (mid + 1 - p); T[i++] = A[q++]; } } while (p <= mid) T[i++] = A[p++]; while (q <= r) T[i++] = A[q++]; for (int j = l; j <= r; j++) A[j] = T[j]; return ans; } int main() { int n; while(scanf("%d", &n) && n) { for(int j=0; j<n; j++) scanf("%d", &A[j]); printf("%lld\n", merge_sort(0, n - 1, A)); } return 0; }
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