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Author: black-shadows

Dynamic Programming/Grid Unique Paths II.cpp

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+long long dp[505][505];
+const int MOD = 1000000007;
+
+int uniquePathsII(vector<vector<int>>& A) {
+    int n=A.size();
+    if(n==0)
+        return 0;
+    int m=A[0].size();
+    if(m==0)
+        return 0;
+    if(A[n-1][m-1]||A[0][0])
+        return 0;
+    for(int i=0; i<n; ++i)
+        for(int j=0; j<m; ++j)
+            dp[i][j]=0;
+    dp[0][0]=1LL;
+    for(int i=1; i<n; ++i)
+        if(A[i][0]==0)
+            dp[i][0]=dp[i-1][0];
+    for(int i=1; i<m; ++i)
+        if(A[0][i]==0)
+            dp[0][i]=dp[0][i-1];
+    for(int i=1; i<n;++i)
+        for(int j=1; j<m; ++j)
+            if(A[i][j]==0)
+                dp[i][j]=(dp[i-1][j]+dp[i][j-1])%MOD;
+    return dp[n-1][m-1];
+}
+int Solution::solve(vector<vector<int> > &A) {
+    return uniquePathsII(A);
+}