字符串 || CodeForces 591B Rebranding

给一字符串，每次操作把字符串中的两种字母交换，问最后交换完的字符串是多少

arr数组记录每个字母最后被替换成了哪个字母

读入字符前面加一空格 scanf(" %c %c", &a, &b); 

#include <iostream>
#include <cstdio>
using namespace std;
#define SZ 200005
char c[SZ];
int main()
{
    int n, m;
    int arr[];
    scanf("%d %d", &n, &m);
    char a, b;
    scanf(" %s", c);
    int len = strlen(c);
    for(int i = ; i < ; i++)
        arr[i] = i;
    for(int i = ; i < m; i++)
    {
        scanf(" %c %c", &a, &b);
        int aa = a - 'a', bb = b - 'a', p, q;
        for(int j = ; j < ; j++) if(arr[j] == aa) {p = j; break;}
        for(int j = ; j < ; j++) if(arr[j] == bb) {q = j; break;}
        arr[p] = bb;
        arr[q] = aa;
    }
    for(int j = ; j < len; j++)
    {
        c[j] = arr[c[j] - 'a'] + 'a';
    }
    printf("%s\n", c);
    return ;
}