数组开多大的问题

// 关键词：逐行逐列
#include <iostream>
using namespace std;
const int N = 110;
int a[N][N];
int n, m;           //n行m列
int main()
{
    cin >> n >> m;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            cin >> a[i][j];
    //逐行逐列扫描
    for (int i = 0; i < n; i++){
        for (int j = 0; j < m; j++) 
            cout << a[i][j] << ' ';
        puts("");
    }
    return 0;
}

例题，矩阵加法

#include <bits/stdc++.h>
using namespace std;
int a[110][110];
int main()
{
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            cin >> a[i][j];
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
        {
            int x;
            cin >> x;
            a[i][j] += x;
        }
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
            cout << a[i][j] << ' ';
        puts("");                        // cout << endl;
    }
    return 0;
}

例题，1127：图像旋转

// 观察，规律
#include <bits/stdc++.h>
using namespace std;
const int N = 110;
int a[N][N];
int n, m;
int main()
{
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            cin >> a[i][j];
    for (int j = 1; j <= m; j++)
    {
        for (int i = n; i >= 1; i--)
            cout << a[i][j] << ' ';
        puts("");
    }
    return 0;
}

例题，1125：矩阵乘法

#include <iostream>
using namespace std;
const int N = 110;
int a[N][N], b[N][N], c[N][N];
int n, m, k; 
int main(){
    cin >> n >> m >> k;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++) cin >> a[i][j];
    for (int i = 1; i <= m; i++)
        for (int j = 1; j <= k; j++) cin >> b[i][j];
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= k; j++){
            for (int p = 1; p <= m; p++)
                c[i][j] += a[i][p] * b[p][j];
        }
    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= k; j++) cout << c[i][j] << ' ';
        puts("");
    }
    return 0;
}

例题，1122：计算鞍点

#include<iostream>
using namespace std;
int a[10][10];
int maxn[10]; 
int minn[10];
int main()
{
    memset(minn, 0x3f, sizeof minn);
    for(int i=1;i<=5;i++)
    {
        for(int j=1;j<=5;j++)
        {
            cin>>a[i][j];
        }
    }
    for(int i=1;i<=5;i++)
    {
        for(int j=1;j<=5;j++)
        {
            if(a[i][j]>maxn[i])
            {
                maxn[i]=a[i][j];
            }
        }
    }
    for(int i=1;i<=5;i++)
    {
        for(int j=1;j<=5;j++)
        {
            if(a[i][j]<minn[j])
                minn[j]=a[i][j];
        } 
    }
    for(int i=1;i<=5;i++)
        for(int j=1;j<=5;j++)
            if(a[i][j]==maxn[i] && a[i][j]==minn[j])
            {
                cout<<i<<' '<<j<<' '<<a[i][j]<<'\n';
                return 0;
            }
    cout<<"not found";
    return 0;
}

例题，2050：【例5.20】字串包含

#include<iostream>
using namespace std;
string s1,s2;
int main(){
    cin>> s1>> s2;
    string s;
    s += s1;
    s += s1;
    if(s.find(s2) != string::npos){
        cout<< "true";
        return 0;
    }
    string ss;
    ss += s2;
    ss += s2;
    if(ss.find(s1) != string::npos){
        cout<< "true";
        return 0;
    }
    cout<< "false";
    return 0;
}

例题，1143：最长最短单词

#include <bits/stdc++.h>
using namespace std;
string s;
int maxn = -1, minn = 1e6;
string r1, r2;
int main()
{
    getline(cin, s);
    for (int i = 0, len = s.size(); i < len; i++){
        if (s[i] == ' ' || s[i] == ',') continue;
        string now;
        int j = i;
        while (j < len && s[j] != ' ' && s[j] != ',') now += s[j++];
        int t = now.size();
        if (t > maxn){
            r1 = now;
            maxn = t;
        }
        if (t < minn){
            r2 = now;
            minn = t;
        }
        i = j - 1;
    }
    cout << r1 << '\n' << r2 << '\n';
    return 0;
}