Number of LCS

Test instructions

Given two strings, A, B, the number of LCS for a, B.

Exercises

In the LCS at the same time calculate the scheme qaq, but stupid I will not, will not, will not ...

Code:

#include <cstdio> #include <cstring> #include <iostream> #include <algorithm>using namespace std;const int mod = 1e9 + 7;const int N = 1e3 + 7;int dp[n][n], Sum[n][n];char ch1[n], Ch2[n];int main () {scanf ("%s%s",  CH1 + 1, CH2 + 1); int n = strlen (ch1 + 1); int m = strlen (CH2 + 1); for (int i = 0; I <= N; ++i) sum[i][0] = 1;for (int j = 0; J <= M; J + +) Sum[0][j] = 1;for (int i = 1; I <= n; ++i) {for (int j = 1; j <= m; ++j) {if (Dp[i][j] < dp[i-1][j]) {dp[i ][J] = dp[i-1][j];sum[i][j] = sum[i-1][j];} else if (dp[i][j] = = Dp[i-1][j]) {sum[i][j] = (Sum[i][j] + sum[i-1][j])% MoD;} if (Dp[i][j] < dp[i][j-1]) {dp[i][j] = dp[i][j-1];sum[i][j] = sum[i][j-1];} else if (dp[i][j] = = Dp[i][j-1]) {sum[i][j] = (Sum[i][j] + sum[i][j-1])% MoD;}  if (ch1[i] = = Ch2[j]) {if (Dp[i][j] < dp[i-1][j-1] + 1) {Dp[i][j] = Dp[i-1][j-1] + 1;sum[i][j] = sum[i-1][j- 1];} else if (dp[i][j] = = Dp[i-1][j-1] + 1) {Sum[i][j] = (Sum[i][j] + sum[i-1][J-1])% mod;}}} printf ("%d\n", Sum[n][m]); return 0;}

　　

Summarize:

A basic DP, I unexpectedly will not qaq, I really for "Zhi several" feel catch urgent ...

Number of LCS