【HDOJ】1513 Palindrome

DP，MLE后改为滚动数组AC。

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cstdlib>
 4
 5 #define MAXN 5001
 6 #define INF 0x3f3f3f3f
 7 char str[MAXN];
 8 short dp[2][MAXN];
 9
10
11 int getmin(int x, int y) {
12     return x<y ? x:y;
13 }
14
15 int main() {
16     int n;
17     int i, j, k;
18
19     while (scanf("%d", &n) != EOF) {
20         scanf("%s", str+1);
21         memset(dp, 0, sizeof(dp));
22         for (i=n; i>0; --i) {
23             k = i&1;
24             for (j=i+1; j<=n; ++j) {
25                 if (str[i] == str[j]) {
26                     dp[k][j] = dp[!k][j-1];
27                 } else {
28                     dp[k][j] = getmin(dp[!k][j], dp[k][j-1]) + 1;
29                 }
30             }
31         }
32         printf("%d\n", dp[1][n]);
33     }
34
35     return 0;
36 }