通过判断是否为一个单词替换后创建新数组并输出

#include <iostream>

using namespace std;

int main()
{
    string s, ow, nw, ns;
    getline(cin, s);
    cin >> ow >> nw;

    for (int i = 0; i < s.size(); i++) {
        if (s.substr(i, ow.size()) == ow && (s[i + ow.size()] == ' ' || s[i + ow.size()] == '\0') && (s[i - 1] == ' ' || s[i - 1] == '\0')) {
            ns += nw;
            i += ow.size() - 1;
        }
        else ns += s[i];
    }

    cout << ns << endl;

    return 0;
}

#include <iostream>

using namespace std;

int cnt;

int main()
{
    string s, res;
    while (cin >> s) {
        res = s + ' ' + res;
    }

    cout << res;

    return 0;
}

利用单词末尾索引和单词的长度打印输出

#include <iostream>

using namespace std;

int idxEnd;  // 单词末尾的索引

int main()
{
    string s;
    getline(cin, s);
    int cnt = 0, maxCnt = 0;  // 最长单词的词数
    int len = s.size();
    for (int i = 0; i < len; i++) {
        if (s[i] != ' ' && s[i] != '.') {
            cnt++;
            if (cnt > maxCnt) {
                maxCnt = cnt;
                idxEnd = i;
            }
        } else {
            cnt = 0;
        }
    }

    for (int i = idxEnd - maxCnt + 1; i <= idxEnd; i++) cout << s[i];

    return 0;
}

#include <iostream>

using namespace std;

char maxV;

int main()
{
    int n;
    cin >> n;
    while (n--) {
        string s;
        cin >> s;
        int maxCnt = 1;
        int cnt = 1;
        maxV = s[0];
        for (int i = 0; i < s.size(); i++) {
            if (s[i + 1] == s[i]) {
                cnt++;
                if (cnt > maxCnt) {
                    maxCnt = cnt;
                    maxV = s[i];
                }
            } else {
                cnt = 1;
            }
        }
        cout << maxV << " " << maxCnt << endl;
    }

    return 0;
}

#include <iostream>

using namespace std;

int main()
{
    string a;
    getline(cin, a);
    int len = a.size();

    for (int i = 0; i < len; ++i) cout << (char)(a[i] + a[(i + 1) % len]);

    return 0;
}

利用判断是否连续为零来打印输出

#include <iostream>

using namespace std;

int main()
{
    string s;
    getline(cin, s);

    for (int i = 0; i < s.size(); i++) {
        if (s[i] == ' ' && s[i + 1] == ' ') continue;
        else cout << s[i];
    }

    return 0;
}

#include <iostream>
#include <cstring>

using namespace std;

int main()
{
    string s1, s2;
    getline(cin, s1);
    getline(cin, s2);

    for (char& c: s1) {
        if (c >= 'A' && c <= 'Z') c += 32;
    }
    for (char& c: s2) {
        if (c >= 'A' && c <= 'Z') c += 32;
    }

    if (s1 == s2) puts("=");
    else if (s1 < s2) puts("<");
    else puts(">");

    return 0;
}

#include <iostream>

using namespace std;

int cnt;

int main()
{
    double k;
    string a, b;
    cin >> k >> a >> b;

    for (int i = 0; i < a.size(); i++)
        if (a[i] == b[i]) cnt++;

    if ((double)cnt / a.size() >= k) puts("yes");
    else puts("no");

    return 0;
}

#include <iostream>
#include <cstring>

using namespace std;

string str, sub;

int main()
{
    while (cin >> str >> sub) {
        string newStr;
        int maxIdx = 0;
        for (int i = 1; i < str.size(); i++) {
            if (str[i] > str[maxIdx]) maxIdx = i;
        }

        newStr += str.substr(0, maxIdx + 1);
        newStr += sub;
        newStr += str.substr(maxIdx + 1);
        cout << newStr << endl;
    }

    return 0;
}

#include <iostream>

using namespace std;

int main()
{
    string s, s2;
    getline(cin, s);

    for (char& c: s) {
        s2 += c;
        s2 += ' ';
    }

    cout << s2 << endl;

    return 0;
}