2020-01-03 13:29:04
問題描述:
![](https://img.laitimes.com/img/9ZDMuAjOiMmIsIjOiQnIsISPrdEZwZ1Rh5WNXp1bwNjW1ZUba9VZwlHdsATOfd3bkFGazxCMx8VesATMfhHLlN3XnxCMwEzX0xiRGZkRGZ0Xy9GbvNGLpZTY1EmMZVDUSFTU4VFRR9Fd4VGdsYTMfVmepNHLrJXYtJXZ0F2dvwVZnFWbp1zczV2YvJHctM3cv1Ce-cmbw5CZlhjM4MDZkRzY2YGM1QjM1QTM4IjM5QWMwETOwETZ38CX0EzLchDMxIDMy8CXn9Gbi9CXzV2Zh1WavwVbvNmLvR3YxUjLyM3Lc9CX6MHc0RHaiojIsJye.png)
public int numDistinct(String s, String t) {
int n1 = s.length();
int n2 = t.length();
int[][] dp = new int[n2 + 1][n1 + 1];
for (int i = 0; i <= n1; i++) dp[0][i] = 1;
for (int i = 1; i <= n2; i++) {
for (int j = 1; j <= n1; j++) {
if (t.charAt(i - 1) == s.charAt(j - 1)) dp[i][j] = dp[i - 1][j - 1] + dp[i][j - 1];
else dp[i][j] = dp[i][j - 1];
}
}
return dp[n2][n1];
}