选择去维护一个最小区间

代码1：

#include<bits/stdc++.h>
using namespace std;
int main() {
    int n;
    cin>>n;
    int num;
    vector <int> v;
    int res=0;
    for(int i=0;i<n;i++){
        cin>>num;
        int loc=v.size();
        int left=0;
        int right=v.size()-1;
        while(left<=right){
            int mid=(left+right)/2;
            if(num>=v[mid]){
                left=mid+1;
            }else{
            	loc=mid;
                right=mid-1;
            }
        }
        if(loc==v.size()){
            res++;
            v.push_back(num);
        }else{
            v[loc]=num;
        }
    }
    cout<<res;
    return 0;
}

代码2：

#include<bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    int x[100005];
    int cnt = 0;
    for (int i = 0; i < n; i++) {
        int y;
        cin >> y;
        int *p = lower_bound(x, x + cnt, y);
        if (p == x + cnt) {
            cnt++;
        }
        *p = y;
    }
        cout << cnt << endl;
        return 0;
}

代码3：

#include<bits/stdc++.h>
using namespace std;
int main() {
    int n;
    cin>>n;
    int num;
    vector <int> v;
    int res=0;
    for(int i=0;i<n;i++){
        cin>>num;
        auto loc=lower_bound(v.begin(),v.end(),num);
        if(loc==v.end()){
            res++;
            v.push_back(num);
        }else{
            *loc=num;;
        }
    }
    cout<<res;
    return 0;
}