75：

	for(int i = 1;i <= cnt; ++i) {
		for(int j = 0;j < a[i]; ++j) dp[i][j] = dp[i - 1][j];
		for(int j = 1000;j >= a[i]; --j) dp[i][j] = max(dp[i - 1][j], dp[i - 1][j - a[i]] + b[i]);
	}

AC:

	for(int i = 1;i <= cnt; ++i) {
		for(int j = 0;j <= 1000; ++j) dp[i][j] = dp[i - 1][j];
		for(int j = 1000;j >= a[i]; --j) dp[i][j] = max(dp[i][j], dp[i - 1][j - a[i]] + b[i]);
	}