CodeForces - 1003B Binary String Constructing

Posted 2022-04-16 海岛Blog

B. Binary String Constructing
time limit per test1 second
memory limit per test256 megabytes

You are given three integers a, b and x. Your task is to construct a binary string s of length n=a+b such that there are exactly a zeroes, exactly b ones and exactly x indices i (where 1≤i<n) such that si≠si+1. It is guaranteed that the answer always exists.

For example, for the string “01010” there are four indices i such that 1≤i<n and si≠si+1 (i=1,2,3,4). For the string “111001” there are two such indices i (i=3,5).

Recall that binary string is a non-empty sequence of characters where each character is either 0 or 1.

Input
The first line of the input contains three integers a, b and x (1≤a,b≤100,1≤x<a+b).

Output
Print only one string s, where s is any binary string satisfying conditions described above. It is guaranteed that the answer always exists.

Examples
input
2 2 1
output
1100
input
3 3 3
output
101100
input
5 3 6
output
01010100
Note
All possible answers for the first example:
1100;
0011.
All possible answers for the second example:
110100;
101100;
110010;
100110;
011001;
001101;
010011;
001011.

问题链接：CodeForces - 1003B Binary String Constructing
问题简述：（略）
问题分析：（略）
AC的C++语言程序（第二版，在第一版基础上修改得来）如下：

/* CodeForces - 1003B Binary String Constructing */

#include <bits/stdc++.h>

using namespace std;

int main()

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int a, b, x;
    cin >> a >> b >> x;
    if (a >= b) 
        cout << '0';
        a--;
        while (x > 2) 
            cout << "10";
            a--, b--, x -= 2;
        
        if (x & 1) 
            while (a--) cout << '0';
            while (b--) cout << '1';
         else 
            while (b--) cout << '1';
            while (a--) cout << '0';
        
     else 
        cout << '1';
        b--;
        while (x > 2) 
            cout << "01";
            a--, b--, x -= 2;
        
        if (x & 1) 
            while (b--) cout << '1';
            while (a--) cout << '0';
         else 
            while (a--) cout << '0';
            while (b--) cout << '1';
        
    

    return 0;

AC的C++语言程序(第一版)如下：

/* CodeForces - 1003B Binary String Constructing */

#include <bits/stdc++.h>

using namespace std;

int main()

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int a, b, x;
    cin >> a >> b >> x;
    if (x & 1) 
        if (a >= b) 
            cout << '0';
            a--;
            while (x > 2) 
                cout << "10";
                a--, b--, x -= 2;
            
            while (a--) cout << '0';
            while (b--) cout << '1';
         else 
            cout << '1';
            b--;
            while (x > 2) 
                cout << "01";
                a--, b--, x -= 2;
            
            while (b--) cout << '1';
            while (a--) cout << '0';
        
     else 
        if (a >= b) 
            cout << '0';
            a--;
            while (x > 2) 
                cout << "10";
                a--, b--, x -= 2;
            
            while (b--) cout << '1';
            while (a--) cout << '0';
         else 
            cout << '1';
            b--;
            while (x > 2) 
                cout << "01";
                a--, b--, x -= 2;
            
            while (a--) cout << '0';
            while (b--) cout << '1';
        
    

    return 0;