题解 | 单词替换

#include <iostream>
#include <vector>
#include <string>
using namespace std;

int main() {
    string str;
    string a, b;
    getline(cin, str); // 注意 while 处理多个 case
    vector<string>v;
    for (int i = 0; i < str.size() ; ) {
        int j = i + 1;
        for (; j < str.size() && str[j] != ' '; ++j);
        v.push_back(string(&str[i], &str[j]));
        i = j + 1;
    }
    cin >> a >> b;
    if (v[0] == a)
        cout << b; 
    else
        cout << v[0];
    for (int i = 1; i < v.size(); ++i) {
        cout << " " << (v[i] == a ? b : v[i]);
    }
}
// 64 位输出请用 printf("%lld")