题解 | #游游的字母翻倍#

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll>PII;
const int N = 2e5 + 10;
const int MOD = 998244353;
const int INF = 0X3F3F3F3F;
const int dx[] = {-1, 1, 0, 0, -1, -1, +1, +1};
const int dy[] = {0, 0, -1, 1, -1, +1, -1, +1};
const int M = 1e6 + 10;

int b[N];
int main()
{
	int n, q;
	cin >> n >> q;
	string s;
	cin >> s;
	while(q --){
		int l, r;
		cin >> l >> r;
	    string o = s;
		int cnt = 0;
		for(int i = l - 1; i <= r - 1; i ++)
		{
		    char c = o[i];
			s.insert(i + cnt ++, 1, c);//在索引i的位置插入1个字符c
		}
	}
	cout << s << endl;
	return 0;
}