2025暑假c++算法笔记📕

输入输出方式

cin cout scanf() printf()

格式:

cin >> cout << 慢（关闭同步流） ios ::sync_with_stdio(false); cin.tie(0);

scanf(“%d”, &x); printf(“%d”,x); 高

效率：数据量在万级一下不明显

cin 返回的是否与容器内容 scanf

#include<bits/stdc++.h>
using namespace std;
const int N = 105;
char arr[N];
int main(){
    int n;
    char x;
    cin >> n;
    for(int i = 1 ; i <= n ; i ++){
        scanf("%c",&x); // 可读取所有字符
        arr[i] = x;
    }
    for(int i = n ; i > 0 ; i --){
        int idx = arr[i]+1;
        if (idx%2 == 0){
            printf("%d ",i);
        }
    }
}

    int n;
    vector <int> a;
    while (cin >> x){
        a.push_back(x);
    }
    sort(a.begin(),a.end());

int x ;
while(cin >> x){ // cin 自动忽略空格，输入数据与容器类型是否一致
}
或
while(scanf("%d",&x) == 1){ // 判断有效的获取数据数量
}
``
![](/projects/book/202507/185095ea352277ad.png)
int n;
while(cin >> n && n !=0 ){
}

#include<bits/stdc++.h>
using namespace std;
int main(){
    int p,x,sum;
    p=1;
    x=15;
    sum=x;
    do{
        p++;
        x+=2;
        sum+=x;
    }while(sum!=312);
    // cout<<x<<endl;
    // cout<<p<<endl;
    printf("%d\n%d\n",x,p);
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
    int x = 0 ;
    do{
        x++;
    }while((x+6)%13 != 0 || (x-6)%12 != 0);
    cout << x << endl;
}

拍手游戏

#include<bits/stdc++.h>
using namespace std;
int main(){
    int time,count,teacher,mingming,meimei;
    bool flag;
    time = 0;
    count = 1;
    teacher = mingming = meimei = 0;
    do{
        flag = 0;
        time++;
        if(teacher < 9){
            flag = 1;
            teacher ++;
        }
        if(mingming < 9 && time%4 == 0){
            flag = 1;
            mingming ++;
        }
        if(meimei < 9 && time % 4 == 0){
            flag = 1;
            meimei ++;
        }
        if(flag) count++;
    }while(teacher + mingming + meimei < 9 * 3);
    cout << count << endl;
    return 0;
}

课堂练习

#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,t,ans;
    n = 1;
    t = 2;
    ans = 0;
    do{
        n=n*t;
        ans += n;
    }while(n <= 1e + 3);
    cout << ans << endl;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
    int num=0,glair=1,nike=1;
    for(int i = 1 ; i <= 1000 ;i ++){
        nike ++;
        glair ++;
        if(nike > 20){
            nike = 1;
        }
        if(glair > 30){
            glair = 1;
        }
        if (nike == glair){
            num ++;
        }
    }
    cout << num;
    return 0;
}

左三角

• 过程

• 代码

等腰三角形

#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,i;
    cin >> n;
    cout << n << "=";
    for(i=2;n!=1;i++){
        while(n%i==0){
            cout << i << " ";
            n = n /2;
            if(n!=1) cout << "*";
        }
    }
    return 0;
}

捉迷藏

#include<bits/stdc++.h>
using namespace std;
bool a[11];
int main(){
    for(int i = 1 ; i <= 10 ; i ++){
        a[i] = true;
    }
    int n = 10;
    a[n] = false;
    for(int i = 1 ; i <= 1000 ; i ++){
        n = (n+i) % 10;
        if(n==0){
            n = 10;
        }
        a[n] = false;
    }
    for(int i = 1 ; i <= 10 ; i ++){
        if(a[i] == true){
            cout << i << endl;
        }
    }
}

#include<bits/stdc++.h>
using namespace std;
int main(){
    int a=0,ans=0;
    string s;
    getline(cin , s);
    for (int i = 0 ; s[i]!='\0' ; i++){
        a ++;
        if (s[i] == '.'){
            ans ++;
        }
    }
    cout << a << endl << ans;
    return 0;
}