Zipper(动态规划)
For example, consider forming "tcraete" from "cat" and "tree":
String A: cat
String B: tree
String C: tcraete
As you can see, we can form the third string by alternating characters from the two strings. As a second example, consider forming "catrtee" from "cat" and "tree":
String A: cat
String B: tree
String C: catrtee
Finally, notice that it is impossible to form "cttaree" from "cat" and "tree".
For each data set, the line of input consists of three strings, separated by a single space. All strings are composed of upper and lower case letters only. The length of the third string is always the sum of the lengths of the first two strings. The first two strings will have lengths between 1 and 200 characters, inclusive.
Data set n: yes
if the third string can be formed from the first two, or
Data set n: no
if it cannot. Of course n should be replaced by the data set number. See the sample output below for an example.
3 cat tree tcraete cat tree catrtee cat tree cttaree
Data set 1: yes Data set 2: yes Data set 3: no
花了好长时间终于用动态规划的方法把样例输入的结果给弄对,但是提交的时候却是WA,后来看了别人的代码发现好多都是用记忆化搜索来做的
AC代码
源代码
#include <stdio.h> #include <string.h> int main() { int i, j, k, t; int L1, L2, ok[202][202]; char str1[201], str2[201], str3[402]; /********************** ok[i][j]为真时表示str1的前i个字符可以和str2的前j个字符 组成str3的前i+j个字符。为假时 表示不能。 ***********************/ scanf("%d", &t); for (i=1; i<=t; i++) { scanf("%s %s %s", str1, str2, str3); memset(ok, 0, sizeof(ok)); L1 = strlen(str1); L2 = strlen(str2); ok[0][0] = 1; for (j=1; j<=L1; j++) { if (ok[j-1][0] == 1 && str1[j-1] == str3[j-1]) ok[j][0] = 1; else break; } for (j=1; j<=L2; j++) { if (ok[0][j-1] == 1 && str2[j-1] == str3[j-1]) ok[0][j] = 1; else break; } for (j=1; j<=L1; j++) { for (k=1; k<=L2; k++) { if (ok[j-1][k]==1 && str1[j-1]==str3[j+k-1] || ok[j][k-1]==1 && str2[k-1]==str3[j+k-1]) ok[j][k] = 1; } } if (ok[L1][L2] == 1) printf("Data set %d: yes\n", i); else printf("Data set %d: no\n", i); } }
WA代码
源代码
#include<stdio.h> #include<string.h> #include<vector> #include<algorithm> #include<iostream> using namespace std; char strr1[1010]; char strr2[1010]; char strr3[1010]; int maxLen[1010][1010]; int main() { int n; scanf("%d",&n); for(int w=1; w<=n; w++) { scanf("%s %s %s",&strr1,&strr2,&strr3); int length1=strlen(strr1); int length2=strlen(strr2); int length3=strlen(strr3); int nTmp; // int i,j,k; memset(maxLen,0,sizeof(maxLen)); for(int i=0; i<=length1; i++) { maxLen[i][0]=0; } for(int k=0; k<=length3; k++) { maxLen[0][k]=0; } for(int i=1; i<=length1; i++) { for(int k=1; k<=length3; k++) { if(strr1[i-1]==strr3[k-1]) maxLen[i][k]=maxLen[i-1][k-1]+1; else maxLen[i][k]=max(maxLen[i-1][k],maxLen[i][k-1]); } } if(maxLen[length1][length3]==length1) { memset(maxLen,0,sizeof(maxLen)); for(int j=0; j<length2; j++) { maxLen[j][0]=0; } for(int k=0; k<length3; k++) { maxLen[0][k]=0; } for(int j=1; j<=length2; j++) { for(int k=1; k<=length3; k++) { if(strr2[j-1]==strr3[k-1]) maxLen[j][k]=maxLen[j-1][k-1]+1; else maxLen[j][k]=max(maxLen[j-1][k],maxLen[j][k-1]); } } if(maxLen[length2][length3]==length2) printf("Data set %d: yes\n",w); else printf("Data set %d: no\n",w); } else printf("Data set %d: no\n",w); } return 0; }
永远渴望,大智若愚(stay hungry, stay foolish)