标签:ios pat roc sam enc col run str size
There is a classical process named partition in the famous quick sort algorithm. In this process we typically choose one element as the pivot. Then the elements less than the pivot are moved to its left and those larger than the pivot to its right. Given N distinct positive integers after a run of partition, could you tell how many elements could be the selected pivot for this partition?
For example, given N=5 and the numbers 1, 3, 2, 4, and 5. We have:
Hence in total there are 3 pivot candidates.
Each input file contains one test case. For each case, the first line gives a positive integer N (≤). Then the next line contains N distinct positive integers no larger than 1. The numbers in a line are separated by spaces.
For each test case, output in the first line the number of pivot candidates. Then in the next line print these candidates in increasing order. There must be exactly 1 space between two adjacent numbers, and no extra space at the end of each line.
5
1 3 2 4 5
3
1 4 5
这题找的是pivot,pivot的定义是,左边比pivot小,右边比pivot大,然后我们可以直接对其进行排序。
条件:1.这个数字索引刚好是排序后索引
2.这个数字在左边最大
#include <iostream> #include <vector> #include <algorithm> using namespace std; int main(){ vector<int> res; int N, Max = -1; cin >> N; int arr[N], cp[N]; for(int i = 0; i < N; i++) { cin >> arr[i]; cp[i] = arr[i]; } sort(cp, cp+N); for(int i = 0; i < N; i++){ if(cp[i] == arr[i] && arr[i] > Max) res.push_back(arr[i]); if(arr[i] > Max) Max = arr[i]; } printf("%d\n",res.size()); for(int i = 0; i < res.size(); i++) if(i != res.size() - 1) printf("%d ", res[i]); else printf("%d", res[i]); printf("\n"); system("pause"); return 0; }
PAT Advanced 1101 Quick Sort (25分)
标签:ios pat roc sam enc col run str size
原文地址:https://www.cnblogs.com/littlepage/p/12230463.html