https://vjudge.net/problem/UVA-11584
题意:
给出一串字符,把它划分成尽量少的回文串。
思路:
用d[i]表示划分到i时所能划分的最小个数,转移方程为d[i]=min{d[i],d[j]+1},当然前提是j+1~i是回文串,我们可以预处理计算出所有的回文串,这样转移时就比较方便。
1 #include<iostream> 2 #include<algorithm> 3 #include<cstring> 4 #include<string> 5 using namespace std; 6 7 const int maxn = 1000 + 10; 8 9 int ans[maxn][maxn]; 10 char a[maxn]; 11 int d[maxn]; 12 13 int main() 14 { 15 //freopen("D:\\txt.txt", "r", stdin); 16 int t; 17 cin >> t; 18 while (t--) 19 { 20 memset(ans, 0, sizeof(ans)); 21 memset(d, 0, sizeof(d)); 22 cin >> a+1; 23 int l = strlen(a+1); 24 25 //打表,判断i~j是否是回文串 26 for (int i = 1; i <= l; i++) 27 { 28 for (int j = i; j <= l; j++) 29 { 30 int left = i, right = j; 31 int ok = 1; 32 while (left <= right) 33 { 34 if (a[left] != a[right]) 35 { 36 ok = 0; 37 break; 38 } 39 left++; 40 right--; 41 } 42 if (ok) ans[i][j] = 1; 43 } 44 } 45 46 d[0] = 0; 47 for (int i = 1; i <= l; i++) 48 { 49 d[i] = d[i-1]+1; 50 for (int j = 1; j <= i; j++) 51 { 52 if (ans[j][i]) 53 d[i] = min(d[i], d[j-1] + 1); 54 } 55 } 56 cout << d[l] << endl; 57 } 58 return 0; 59 }