The Preliminary Contest for ICPC China Nanchang National Invitational M题 Subsequence

题意：给你一个文本字符串P，n个字符串si，然后判断字符串si是不是文本串P的子序列

枚举给个字符最早出现的位置就可以了
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 5;
char s[maxn];
int pos[maxn][30];
int dis[maxn];
int main() {
	scanf("%s", s + 1);
	int n = strlen(s + 1);
	
	for(int i = n; i >= 1; i--) {
		for(int j = 0; j <= 26; j++) {
			pos[i][j] = pos[i + 1][j];
		}
		pos[i][s[i] - 'a'] = i;
		dis[s[i] - 'a'] = i;
	}
	scanf("%d", &n);
	for(int i = 1; i <= n; i++) {
		scanf("%s", s + 1);
		int m = strlen(s + 1); 
		int start = dis[s[1] - 'a'];
		if(start == 0) {
			printf("NO\n");
			continue;
		}
		int flag = 1;
		for(int j = 2; j <= m; j++) {
			if(pos[start + 1][s[j] - 'a'] == 0) {
				flag = 0;
				break;
			}
			start = pos[start + 1][s[j] - 'a'];
		}
		if(flag) {
			printf("YES\n");
		} else {
			printf("NO\n");
		}
	} 
	return 0;
}