1. First look at the most basic usage
#include<iostream>
#include<algorithm>//sort函数的头文件
#include<vector>
using namespace std;
bool cmp(int a,int b)
{
return a>b;
}
int main()
{
int n;
cin>>n;
int a[n];
//vector<int>a(n);
for(int i=0;i<n;i++) cin>>a[i];
sort(a,a+n);//sort函数默认排序是升序的
for(int i=0;i<n;i++) cout<<a[i]<<' ';
cout<<endl;
sort(a,a+n,cmp);
for(int i=0;i<n;i++) cout<<a[i]<<' ';
cout<<endl;
return 0;
}
Sample input:
10
1 0 9 7 6 5 3 2 4 8
Sample output:
0 1 2 3 4 5 6 7 8 9
9 8 7 6 5 4 3 2 1 0
Among them, sort(a,a+n) is the default sorting, which is ascending;
sort(a,a+n,cmp) adds a cmp function to change the sorting method to descending order
2. Used to arrange the parts in the array number
#include<iostream>
#include<algorithm>//sort函数的头文件
#include<vector>
using namespace std;
bool cmp(int a,int b)
{
return a>b;
}
int main()
{
int n;
cin>>n;
//int a[n];
vector<int>a(n);
for(int i=0;i<n;i++) cin>>a[i];
cout<<endl;
sort(a.begin()+2,a.end()-2);
for(int i=0;i<n;i++) cout<<a[i]<<' ';
cout<<endl<<endl;
sort(a.begin()+2,a.end()-2,cmp);
for(int i=0;i<n;i++) cout<<a[i]<<' ';
cout<<endl<<endl;
return 0;
}
Sample input:
10
0 2 1 4 3 8 6 7 5 9
Output:
0 2 1 3 4 6 7 8 5 9
0 2 8 7 6 4 3 1 5 9
Here sort(a.begin()+2,a.end()-2);, +2 and -2 indicate the first two, and the last two do not participate in the arrangement;
Note here the array int a[n];replaced vector<int>a(n);
used vector<int>a(n);to use when the header file #include<vector>
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The usage of cmp function here is the same as above.
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