[itint5]棋盘漫步

要注意dp[0][0]要初始化为1。

int totalPath(vector<vector<bool> > &blocked) {
    int m = blocked.size();
    if (m == 0) return 0;
    int n = blocked[0].size();
    if (n == 0) return 0;
    vector<vector<int> > dp(m);
    for (int i = 0; i < m; i++) {
        dp[i].resize(n, 0);
    }
    if (!blocked[0][0]) dp[0][0] = 1;
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (blocked[i][j]) {
                dp[i][j] == 0;
            } else {
                if (i-1 >= 0) dp[i][j] += dp[i-1][j];
                if (j-1 >= 0) dp[i][j] += dp[i][j-1];
            }
        }
    }
    return dp[m-1][n-1];
}