题意:正则表达式匹配
思路:DP dp[i][j]表示b串中0~i与0~j是否可以匹配,具体的转移看代码:
#include<cstdio> #include<cstring> #include<string> using namespace std; const int maxn=2600; char a[maxn],b[maxn]; bool dp[maxn][maxn]; int main() { freopen("input.txt","r",stdin); int T;scanf("%d",&T); while(T--) { scanf("%s%s",a+1,b+1); memset(dp,0,sizeof dp); dp[0][0]=1; int sa=strlen(a+1),sb=strlen(b+1); for(int i=1;i<=sb;i++) { if(b[i]==‘*‘&&i>=2)dp[i][0]=dp[i-2][0]; for(int j=1;j<=sa;j++) { if(b[i]==a[j] || b[i]==‘.‘)dp[i][j] = dp[i-1][j-1]; else if(b[i]==‘*‘) { dp[i][j] = dp[i-1][j] | dp[i-2][j]; dp[i][j] |= dp[i-1][j-1]&&(a[j]==a[j-1]); if(dp[i-1][j]) { while(j<=sa&&a[j]==a[j+1])dp[i][++j]=1; } } } } if(dp[sb][sa]) printf("yes\n"); else printf("no\n"); } return 0; }
原文:http://www.cnblogs.com/MeowMeowMeow/p/7419633.html