LeetCode 115. Distinct Subsequences

#include <string>#include <vector>#include <iostream>using namespace std;// for example, S = "ABCDE", P = "AEC" --> return 1// for example: S = "rabbbit", P = "rabbit" --> return 3.int distinctSubsequences(string s, string t) {  int m = t.size(), n = s.size();  vector< vector<int> > dp(m + 1, vector<int>(n+1, 0));  for(int i = 0; i <= m; ++i) {    for(int j = 0; j <= n; ++j) {      if(i == 0) dp[0][j] = 1; // empty string can always match.      else dp[i][j] = (t[i-1] == s[j-1]) * dp[i-1][j-1] + dp[i][j-1];    }  }  return dp[m][n];}int main(void) {  cout << distinctSubsequences("AABC", "AC") << endl;}