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POJ2299 Ultra-QuickSort 【树状数组】+【hash】
Ultra-QuickSort
Time Limit: 7000MS | Memory Limit: 65536K | |
Total Submissions: 39529 | Accepted: 14250 |
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
注意结果要用long long存储。
#include <stdio.h> #include <string.h> #include <algorithm> #define maxn 500002 using std::sort; int tree[maxn], ori[maxn], hash[maxn]; long long ans; int getHash(int val, int n) { int left = 0, right = n - 1, mid; while(left <= right){ mid = (left + right) >> 1; if(val < hash[mid]) right = mid - 1; else if(val > hash[mid]) left = mid + 1; else return mid + 1; } } int lowBit(int pos){ return pos & (-pos); } int getSum(int pos) { int sum = 0; while(pos > 0){ sum += tree[pos]; pos -= lowBit(pos); } return sum; } void update(int pos, int n) { ans += (pos - 1 - getSum(pos - 1)); while(pos <= n){ ++tree[pos]; pos += lowBit(pos); } } int main() { int n, i; while(scanf("%d", &n), n){ for(i = 0; i < n; ++i){ scanf("%d", ori + i); hash[i] = ori[i]; } sort(hash, hash + n); for(i = 0; i < n; ++i) ori[i] = getHash(ori[i], n); memset(tree, 0, sizeof(tree)); ans = 0; for(i = 0; i < n; ++i) update(ori[i], n); printf("%lld\n", ans); } return 0; }
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