POJ 1458 Common Subsequence DP(LCS)

題意：求最大公用子序列
題解：
當 i = 0 或者 j = 0 時 , c[i][j] = 0

當 i , j > 0 ; xi = yi 時 , c[i][j] = c[i-1][j-1] + 1

當 i , j > 0 ; xi != yi 時 , c[i][j] = max { c[i][j-1] , c[i-1][j] }

#include <cstring>#include <iostream>using namespace std;#define N 1001char str1[N], str2[N];int dp[N][N];int max ( int a, int b ){return a > b ? a : b;}int main(){int len1, len2, i, j;    //freopen("a.txt","r",stdin);while ( scanf("%s %s", str1 + 1, str2 + 1 ) != EOF ){len1 = strlen(str1+1);len2 = strlen(str2+1);for ( i = 0; i <= len1 || i <= len2; i++ )dp[i][0] = dp[0][i] = 0;for ( i = 1; i <= len1; i++ ){for ( j = 1; j <= len2; j++ ){if ( str1[i] == str2[j] )dp[i][j] = dp[i-1][j-1] + 1;elsedp[i][j] = max ( dp[i-1][j], dp[i][j-1] );}}printf("%d\n",dp[len1][len2]);}return 0;}