Submission #2152621

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

const int N = 500005;

int n, q;
int nxt[N][30];
int rmq[N][20];
string s;

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	cin >> s >> q;
	n = s.size();

	for (int j = 0; j <= 26; ++j) nxt[n][j] = nxt[n + 1][j] = n + 1;

	for (int i = n - 1; i >= 0; --i) {
		nxt[i][s[i] - 'a' + 1] = i + 1;
		for (int j = s[i] - 'a' + 2; j <= 26; ++j) {
			nxt[i][j] = nxt[nxt[i][j - 1]][j - 1];
			// the remaining string contains only one character: j
		}
		nxt[i][0] = nxt[nxt[i][26]][26]; // empty string

		for (int j = 1; j < s[i] - 'a' + 1; ++j) {
			nxt[i][j] = nxt[nxt[i][0]][j];
		}
	}

	for (int i = 0; i <= n + 1; ++i) rmq[i][0] = nxt[i][0];
	for (int j = 1; j <= 19; ++j) {
		for (int i = 0; i <= n + 1; ++i) rmq[i][j] = rmq[rmq[i][j - 1]][j - 1];
	}

	while(q--) {
		int l, r; cin >> l >> r;
		--l;
		// r = nxt[l], nxt[nxt[l]], ...
		for (int i = 19; i >= 0; --i) {
			if (rmq[l][i] <= r) l = rmq[l][i];
		}
		printf("%s\n", (l == r) ? "Yes" : "No");
	}
}

Submission Info

Judge Result