题解 | #字符串操作#

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int m = scan.nextInt();
		String str = scan.next();
		char[] arr = new char[n+1];
		for(int i = 1;i < arr.length;i++) {
			arr[i] = str.charAt(i-1);
		}
		int l = 0, r = 0;
		char c1 = 0, c2 = 0;
		while (m > 0) {
			l = scan.nextInt();
			r = scan.nextInt();
			c1 = scan.next().charAt(0);
			c2 = scan.next().charAt(0);
			for(int i = l;i<=r;i++) {
				if(arr[i]==c1) {
					arr[i] = c2;
				}
			}
			m--;
		}
		for(int i = 1;i < arr.length;i++) {
			System.out.print(arr[i]);
		}
	}
}