HDU 1501: (DFS)

Do not know why has been overtime, and finally added a pruning on it: The last letter of the synthetic word should be at least the same as the last letter of one of the previous two words

#include "Cstdio" #include "Cmath" #include "CString" #include "iostream" #define MAXN 205using namespace Std;char arr[4][ Maxn];int len[4];int vis[maxn][maxn];int p=1,ok;void dfs (int x,int y,int z) {   if (OK) return;    if (Z>=len[3]) {Ok=1;return;}    if (Vis[x][y]) return;    if (Arr[1][x]==arr[3][z]) {        vis[x][y]=1;        DFS (x+1,y,z+1);        vis[x][y]=0;    }    if (Arr[2][y]==arr[3][z]) {        vis[x][y]=1;        DFS (x,y+1,z+1);        vis[x][y]=0;}    } int main () {   int n;    scanf ("%d", &n);    while (n--) {        scanf ("%s%s%s", arr[1],arr[2],arr[3]);        for (int i=1;i<=3;i++)            Len[i]=strlen (Arr[i]);        ok=0;        memset (vis,0,sizeof (Vis));        if (arr[1][len[1]-1]==arr[3][len[3]-1]| | ARR[2][LEN[2]-1]==ARR[3][LEN[3]-1])            DFS (0,0,0);        if (OK) printf ("Data set%d:yes\n", p++);        else printf ("Data set%d:no\n", p++);    }    return 0;}

HDU 1501: (DFS)